Mirror Neurons and Skilful Coping

MIRROR NEURONS AND SKILFUL COPING: MOTOR INTENTIONALITY BETWEEN SENSORIMOTOR AND IDEO-MOTOR SCHEMATA IN GOAL-DIRECTED ACTIONS Abstract I approach philosophically mirror neuron theory by situating it between the sensorimotor and the ideo-motor approaches to skilful coping. Mirror neuron theorists have developed their account of goal-oriented action under the influence of Merleau-Ponty’s concept of motor intentionality. I compare it to the Merleau-pontian description of motor intentionality proposed by Hubert Dreyfus, showing that his account stresses prominently a sensorimotor model of skilful coping, and that – for this reason – it can only partly match the embodiment of motor goals in mirror functions. I analyze then Wolfgang Prinz’s model of William James’ motor ideas, showing that it is symmetrical under many aspects to Dreyfus’ model, and that – for this reason – it explains only the other half of the motor intentional process. I propose to consider sensorimotor and ideo-motor approaches to goaloriented actions as reciprocally linked and complementary. From the phenomenological point of view, this means that, while motor intentionality instantiated by the former aims to an optimal equilibrium between body and world, the motor intentionality instantiated by the latter aims to break this equilibrium. From the empirical point of view, it means that the former derives motor goals through a bottom-up process of inductive abstraction of kinaesthetic invariants, while the latter filters the meaning of kinaesthetic experiences by means of a top-down process which is shaped within the boundaries of primary goal-related motor ideas. I show that mirror functions can constitute the condition of reversibility for the two approaches; but I also stress that only mirror functions codify the intentional meaning of the action in a fully-embodied way, because they express goals in an originary motor format. Mirror neurons and the definition of goal-oriented intentional actions Experiments carried out by Giacomo Rizzolatti’s parmesan research group show that mirrorneurons-related motor schemata of purposeful transitive behaviours are activated not only when a subject is executing an action, but also when he is observing the same action while it is performed. Recordings with microelectrodes implanted in single cells of macaque ventral premotor cortex show that each one of the different mirror neuron circuits responds selectively to a type of transitive goaloriented actions like grasping, placing, holding, crushing, ripping, bringing to mouth1. That’s why mirror neuron theory affirms that motor schemata related to the activation of mirror neurons pertain to goal-oriented actions and express, at once, an executive valence and a cognitive-perceptual one. 1 Gallese et al (1996). 1 Differential analysis2 has progressively made clear that their response does depend neither on the identity of the agent (potentially anyone performing the action)3, nor on the object targeted by the action (as long as it allows that specific kind of action), nor on the involved effectors (left hand, right hand, mouth or tools, as long as they allow the same kind of practical intervention), nor on the kinematics of the gesture (e.g. grasping from the top, from the bottom4, or through a non-natural kinematical strategy by means of a tool5), nor on distality (and this excludes the influence of a volitional attitude, i.e. the desire to perform the gesture). The criteria for mirror neuron activation are tolerant enough to result insensitive to different kinematical strategies and to different effectors involved, as long as they aim to the same goal; at the same time, mirror neuron circuits are selective enough to distinguish extremely similar kinematical strategies, as long as they display different goals. This means that the same “grasping” mirror neuron circuit in the macaque brains is activated by very heterogeneous movements with hands, mouth or pliers, as long as they are meant to grasp something, but the same movements do not trigger the activation of mirror neurons if they are not directed to that concrete goal. From the point of view of the embodied motor skills of a macaque, it is only secondary what trajectories are drawn by its movements and what body parts are involved in order to grasp a nut with the fingers, but it is primarily relevant that the macaque grasps it with an expectation of a successful result. By undermining the syntactical role of the kinematical structure, the experiments have always confirmed that every mirror neuron circuit corresponds specifically to the intentional, purposeful meaning of the kind of action it is associated to (Fogassi et al. 2005), independently from the fact that the action is actually performed or merely perceived: in the former case we shall argue that the intentional meaning is actually expressed by the body as an executive behavioural schema accessed in a first-person-perspective, while in the latter it seems that the intentional meaning is accessed in a third-person-perspective and recognized as a potentially executable purposeful motor schema. The intentional meaning is accessible then in either a performative or in a perceptual way, but what is most important is that it is always mapped in a motor format, accessible during execution and recognition tasks. The discovery of mirror neurons is extremely relevant just because they consist in premotor structures that display cognitive functions besides control functions: this suggests that the agent, by means of his own bodily proficiencies, already govern a “motor knowledge”6 of the potentially disposable actions that is pre-reflectively operating before and below the higher levels of intelligent processes. The classical cognitivistic paradigm of motricity is put into question by this discovery, because it shows that motor and premotor areas are not only involved in execution and control of the action, but also in cognitive tasks related to recognition, categorization and prediction7 of the intentional meaning of the actions. This new framework gives finally flesh to a fully embodied scheme of cognition, because the knowledge of basic goals of motor actions is intrinsic to the executive/perceptual processes and not derived from them: senses and motricity are not the two opposite extremities of the main process of 2 Rizzolatti & Sinigaglia (2007a) is the most comprehensive text on this subject. It reports and comments many of the experimental evidences mentioned here. 3 Gallese et al. (2002). 4 Rizzolatti, Fogassi, Gallese (2001). 5 The experiment with “reverse pliers” performed by Umiltà et al. (2008) confirms that mirror neurons respond to motor goals independently from the kind of movements involved. Reverse pliers constitute a very peculiar tool because the goal of grasping can be performed by the monkey only when it learns that opening the hand causes the pliers to close, and vice versa. “The use of pliers requires the capacity to separate a proximal goal (grasp the pliers) from a distal goal (grasp an object), a distinction that is not present in natural actions in which the two goals coincide […].” The experiment shows that the transfer between hand-grasping and tool-use motor schemata, with the consequent incorporation of tools in a familiar bodily schema, “occurs not only when the mechanics of pliers mimics that of the hand (normal pliers), but also when the mechanics is its exact opposite. Also in this case the distal goal, i.e., grasp the object by opening the hand, is the pivotal element around which movements are organized.” 6 Rizzolatti & Sinigaglia (2007a, p. 205). 7 Fogassi et al. (2005). 2 elaboration (like in the classical sandwich-like cognitivistic framework: “input-computationoutput”). The motor process is in facts intrinsically endowed with a cognitive meaning which is quasi-independent from previous or higher processes of elaboration. In a few words, this confirms a classical principle of Merleau-pontian phenomenology according to which the body already holds some knowledge about how to act intentionally before and below any mental process of representational or symbolical elaboration concerning how the action is structured8. This principle resonates with Rizzolatti’s idea that mirror neuron circuits form a built-in vocabulary of simple intentional goals expressed in motor terms9, codified as open-ended schemata for general practical intentions, and not as instantiations of single definite movements. From the evolutionary, the functionalist and the phenomenological point of view, the basic motor repertoires are more efficiently and economically organized, retrieved and enacted by patterns of expected motor effects (goals) than by patterns of movements. It is phenomenologically relevant that, when an agent performs a purposeful action, the conscious experience of acting in a goal-oriented way depends neither on the complex of stimuli that he perceives from his body, nor on the topological coordinates of his anatomical parts; and also when a subject recognizes the intentional meaning of an action performed by someone else, the recognition is derived by the holistic evidence of the meaningful purpose of the action, and not by some neutral elaboration of the meaningless topological modifications occurring in the agent’s system of body parts10. This phenomenological evidence finds in mirror neuron theory a promising counterpart for what concerns its sub-agential neurological implementation. Given the priority of the holistic purposeful meaning over the collection of disconnected sensorimotor stimuli, the discovery of mirror neurons confirms this phenomenological evidence by suggesting that proprioception and somatosensory information are not the only required elements (and not the most fundamental ones) in order to control/recognize goal-oriented intentional actions11. Experiments on mirror neurons have shown that the intentional meaning concerns purposes as it corresponds to the “how-to” knowledge that associates motor goals to bodily actions. Mirror functions are functionally defined neither by the syntax of the kinematic structure of simple movements (the coordinates that have been altered in the topology of the body-environment system), nor by the semantics of the concepts behind the motivation of the action (beliefs, knowledge, mental representations and so on); rather, they are defined by the pragmatics of the action (i.e. the consequences of the action for the life of the agent and for its essential embodied experience). This pragmatist principle circumscribes the applicability of the cognitivistic assumption according to which the goal of the action is a formal content (a mental representation) ontologically independent from the material conditions in which the body operates and logically separable from the environmental situation in which the action takes place12. The intentional 8 Kelly (2002, p. 377) has admirably synthesized this point by showing the dissociation between cognitive intentionality and motor intentionality: “The understanding of space that informs my skillful, unreflective bodily activity […] is not the same as, nor can it be explained in terms of, the understanding of space that informs my reflective, cognitive or intellectual acts – acts such as pointing at the doorknob in order to identify it.” 9 Rizzolatti et al. (1988); Rizzolatti & Gentilucci (1988). 10 This is one of the main claims of Dreyfusian phenomenological analysis: meaningful contents of experience can’t be derived by the combination of meaningless elements. For this reason the frame problem can’t be solved by adding more and more instructions into the program governing the machine. 11 Even though I’m the only responsible for eventual mistakes, my thesis is abundantly in debt with Corrado Sinigaglia’s teaching and constitutes a free philosophical interpretation of his theory of motor intentionality. About the priority of goals over perceived movements, see Rizzolatti & Sinigaglia (2007b, p. 207): “mirror neurons map the sensory representations induced by observing the actions of others onto the motor goal-centered representations of those same actions. Without this mapping, at best the sensory representations would be able to provide a description of the various sensory aspects of the observed movements, but they would not be able to pick up their intentional meaning, i.e. what these movements are about, their motor goal, and how they are related to other motor acts”. 12 A famous (and widely discussed) fMRI study performed by Iacoboni et al. (2005) on human premotor cortex shows that the neural patterns activated during the observation of a purposeful action are similar to the patterns activated by the most congruent contextual situation: in facts, “context suggested the intention associated with the grasping action 3 meaning of the action is not a formal semantic structure exportable and identically reproducible in infinite contexts, because the bodily action and its environmental scenario – in order to be meaningful – must belong to each other and can never be completely isolated. No dualism between body and world can account for the intentionality embedded in mirror-neurons-related practical schemes of actions, because the motor-goal is embodied in the very movements allowing the action, and the action itself is embedded with the contextual meaning of the environment in which it takes place: in facts, the purposeful schemata of the intentional actions can’t be defined independently from their bodily realization (even if multiple movements can instantiate the same motor purpose), and motor schemata are always associated with the open-ended range of their pertinent environmental contexts (even if different contexts can solicit the same motor response)13. But, if the goal of the action is not derived from the perceived movements and is not even a concept, what is it then? Attractor basins and mirror neurons: motor intentionality and skilful coping according to Hubert Dreyfus Phenomenology helps to answer this question describing the dynamic systemic relationship undergoing between goal, body and environment in intentional actions related to mirror neurons. This relationship is accounted for by the notion of motor intentionality, that Giacomo Rizzolatti and Corrado Sinigaglia (2007b) have developed by re-interpreting a central notion of Maurice MerleauPonty’s Phenomenology of Perception. During the last years, motor intentionality has also been in the spotlight of an important debate in philosophy of mind, which flourished around Hubert Dreyfus’ decisive article “A Merleau-Pontyian Critique of Husserl's and Searle's Representationalist Accounts of Action” (2000), and around Sean Dorrance Kelly’s studies (2000, 2002) on the Phenomenology of Perception. In the present context it seems particularly interesting to compare the interpretations of motor intentionality given by mirror neuron theorists and by Dreyfus. According to Merleau-Ponty’s phenomenology, and to the influential philosophical interpretation that Dreyfus has given of it, motor intentionality consists in a sort of tension experienced through the body; this tension is endowed with purposeful meaning and motivates goal-oriented actions like the ones enacted by mirror neurons. According to this phenomenological point of view, motor intentionality is inseparable from its bodily context and from the environment in which action takes place, and this happens to be necessarily true for a very simple reason: according to a sensorimotor account of action, an agent performs an intentional motor-action as soon as he is seeking an adequate response of his body to the environmental situation; consequently, the intentional meaning of the action is exactly determined by the ongoing dynamic relation of adequacy/inadequacy between body and world. According to Dreyfus, the refinement of already familiar motor skills, or the acquisition of new ones, is mediated by the agent’s capability of modulating bodily responses to solicitations offered by the situations; this capability doesn’t consist in a simply mechanical reactivity or in a set of instructions stored in the subject’s mind, but in “a disposition” of the body to compensate the contextual circumstances. The development of these “skilful” dispositions is governed by the agent’s “sense of an optimal gestalt”: the agent’s body gradually modifies its responses to the (either drinking or cleaning)”. This confirms that a goal-oriented action and a situation supporting its goal belong somehow to each other and are co-implicated in the same cognitive/motor processes: “thus, premotor mirror neuron areas – areas active during the execution and the observation of an action – previously thought to be involved only in action recognition, are actually also involved in understanding the intentions of others. To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically.” 13 That’s why “when the sensory stimuli are ambiguous, the activation of one or more intentionally connected motor representations helps us to decipher the intentions of others. We are then able to choose the intention that appears to be most compatible with the context, to the point of identifying the most appropriate one” (Rizzolatti & Sinigaglia 2007b, p. 209). 4 perceived solicitations in accordance with environmental feedbacks. This process goes on until the agent’s body comes to fit perfectly the environment, reaching a dynamical equilibrium with it. The action of the agent, modulated by the body-environment situation, is clearly intelligent and intentional, because it aims to the fulfillment of a practical purpose; nonetheless, during this process, the agent doesn’t access any representation of the optimal gestalt, nor he possesses an already defined set of behavioural rules that would consent him to plan his actions; the gestalt toward which his actions tend is not mentally depicted but it is simply sensed as a force camp attracting the agent’s bodily movements. The agent doesn’t foresee in advance the situation in which his body will be when it will have accomplished its motor purpose, but he can sense how distant from the optimal situation his body is, and he can sense in which direction he should orient his movements in order to reduce the sense of inadequacy engendered by this distance. The process necessary to achieve the optimal state is called “maximal grip” by Merleau-Ponty, and indicates that an intentional agent is motivated to adapt to the situation in the smoothest and most harmonious way through his body, so to get closer and closer to the condition of virtual equilibrium that Dreyfus has called “optimal [or satisfactory] gestalt”. The continuous adaptive relation between agent and world is called “intentional arc”: this concept presupposes that intentionally structured reactive behaviors (coping) are endowed with the meaning of their conscious (intentional) embodied experience; the phenomenological notion of intentional arc contains the idea that the meaning of the action and its contextual background are not only strongly associated, but also codeterminated by their relation of reciprocity, so that every environment displays an intentional meaning by means of the actions that might be performed in it, and every action has some intentional meaning because of its possibility to entertain relations with endless environmental situations. This kind of goal-oriented actions (not only the actually performed ones, but also the potentially disposable ones) modulates the relation between the agent’s body and its environmental situation, so that both of them owe their intentional meaning from the agent’s capability of acting adequately. Dreyfus has acknowledged that not every intentional motor action is dependent on such intelligent, goal-oriented, highly adaptive, pre-reflective, not-necessarily aware and non-representational process, since many intelligent behaviors, especially in human beings, are explicitly planned and rationally structured14. Dreyfus’ account is restricted to coping, as it consists in a very fundamental bodily activity that is prominently guided and controlled by motor intentionality. From now on, I’m going to use the term “skilful coping”, already used by Dreyfus in his exchange with Michael Wheeler15, in order to indicate the intentional actions that instantiate specifically goal-directed processes of harmonization between body and world. Each kind of skilful coping is endowed with a distinct finalistic sense that, however, depends only from the bodily capacity to counterbalance the environmental stimuli so to reduce the sense of deviation from a satisfactory gestalt. According to the mathematical models of artificial neural nets developed by neuroscientist Walter Freeman16, and revisited by Dreyfus in a phenomenological frame, each purposeful action describable as skilful coping is guided by its specific attractor basin, which governs neuronal activity by bringing it to reach in a specific way its minimal level of energy; each attractor basin is phenomenologically equivalent to the gestaltic force camp that guides and reshapes the motor experience by soliciting the agent to achieve a satisfactory adaptation to its contextual situation. It is very interesting that Dreyfus-Freeman’s account of skilful coping seems at least hypotetically compatible – under some conditions - with mirror neuron theory, and notably with the theory of a vocabulary of basic motor goals. Mirror neurons theorists explicitly mention the Merleau-pontian concept of motor intentionality for describing the dual performative/perceptual competence that is possessed by the body and that is enacted by the premotor cortex; this confirms that Merleau14 However, even very rational behaviors, like moving chess pieces in fast playing, can be instantiated by skilful coping as long as their meaning is so familiar and unreflective to become fully embodied. See Dreyfus (2002b). 15 See Wheeler (2005, 2008) and Dreyfus (2008). 16 Freeman (1991). 5 Ponty’s phenomenology of embodiment is still offering priceless suggestions to neuroscientific research and to philosophical studies. Apparently, an important part of mirror neurons theory can be immediately described in the framework provided by Dreyfusian analysis: if we think that each kind of simple, adaptive and goal-oriented actions corresponding to a mirror neuron circuit consists in a specific type of skilful coping, we are easily brought to assume that this circuit might work like (or together with) an attractor basin which directs the motor intentionality of the agent toward the fulfilment of his bodily purpose, without that any representation of the purpose were necessary. This would account for mirror neurons capacity of codifying actions which are endowed with motor goals, which are simple, non-representationally codified, although their kinematics is structured in an open-ended way that is also highly adaptive to different practical contexts. Both mirror neurons and skilful-coping-related attractor basins are concerned with specific goaloriented intentional skills possessed by the body, and this suggests that the two theories can be reciprocally enriched and clarified by their unification, as long as this is allowed by their own specific assumptions. In reality this unification would be possible only if the functioning of the attractor basins for motor intentionality might display a basilar performative valence and a secondary perceptual one at the same time, exactly like mirror systems do; two different types of experiential contents (perception and motor activity) should be completely matched (1), and moreover their information should be stored in a motor format (2). About (1), it is plausible that Freeman’s attractor basins could match perceptual states (e.g. a particular smell of food, like banana) and motor reactions (biting the banana)17. Motor reactions can produce a “reward” for the perceptual activity and thus strengthen the functional disposition of the basins. The basins might map in a twinned, temporary and elastic structure both perceptual stimuli and motor responses, but they are still two functionally separate moments of the cognitive process; also mirror neurons match perceptual stimuli and motor programs, but their matching is deeply rooted in pragmatics, and it is also more strict and specific, since the perceptual stimuli that are matched with the motor responses pertain exactly to the very intentional meaning of the action that is codified by the circuit (then the action related to that circuit is not coupled with whatever sensory feedback, but with the specific perceptual aspects of the goal-oriented action itself). In both cases, anyway, the perceptual elicitation of the neural structures initialize a behavioural program that not necessarily has to be expressed, in facts it can just be inhibited and made present as a simple virtual opportunity of intervention in the world; but it is crucial that this potential consists just in a perceptual schema according to Freeman’s basins, while in the case of mirror neurons it displays a concrete practical motor significance, concerning how the action must be structured. By means of mirror neurons, the acquisition and the improvement of motor expertises, like the ones enacted by attractor basins, is useful both for triggering one’s own actions and for immediately understanding the actions of other agents. The comprehension of other agents’ intentional actions is always mediated by one’s own motor expertise18, and this principle can be made compatible with Dreyfus model of embodied expertise, under some conditions. Hypothetically, we can imagine that mirror neurons work like (or in accordance with) a very peculiar variety of attractor basins instantiated in the premotor cortex; and the attractor basins theory, then, might be developed in order to explain how the same neural structure could be exploited either in an executive or in a solely perceptual task. This would better explain how the process of harmonization between body and world driven by intentional arc can proceed through both pathways, from action to perception and from perception to action, reversibly, in a continuous loop of sensorimotor feedbacks. Of course, to propose this hypothetical equivalence doesn’t amount to suppose that mirror neurons circuits instantiate attractor basins like the ones described by Freeman, since it is not mandatory that the two structures coincide from the strict anatomical-functional point of view; it is sufficient that their processes, even if distinct and operating with different strategies, could parallely cooperate for 17 18 Freeman (1991). See Calvo-Merino 2005. 6 enacting the kind of intentional arc which is needed in skilful coping. So I don’t think that, at least in the present theoretical discussion, the empirical evidence of some anatomical-functional discontinuity could really matter. There are other and conceptually more relevant problems that prevent a full unification of Dreyfus-Freeman’s theory of motor intentionality and mirror neuron theory. The main problem in unifying the two theories, then, is not that the attractor basins couldn’t have in principle a dual and reversible function, like mirror neurons do; rather, the problem is (2) that the basic type of expertise corresponding to the activation of mirror neurons concerns organized motricity, and not somatosensory or perceptual information19. On the contrary, the attractor basins, at least the ones described by Freeman and then by Dreyfus, contain expertise only in a perceptual format, because they correspond to a force camp that defines how some possible perceptual situations might provoke some compensative movements. Mirror neurons codify primarily “how I should act according to my goal”, while attractor basins “what I should perceive in order to act”. Sensorimotor processes are not enough The difficulty arising at the level of the functional implementation is even more perspicuous from a general conceptual point of view, and pertains to the limits of the sensorimotor approach to action. I intend to refer here to the fact that, although Dreyfus’ model of skilful coping is always described as an embodied sensorimotor process, mirror neuron functions seem to be engaged also in ideo-motor processes, and moreover they seem highly connected to motor ideas. The Dreyfusian description of motor intentionality, in facts, illustrates skilful coping by means of a device that keeps a continuous compensative adherence between body and environment only by means of a correction of the movements depending on the associated perceptual feed-back20: this seems to work very well in tasks requiring the body to be constantly guided by the cues offered by the environment, until reaching an equilibrium with it (for example while we drive a car and we need to change the gear in accordance with the sound of the engine and with the view of the road; or when, in a museum, we move nearer and farer from the wall in order to find the perfect distance for admiring a hanging painting). Generally speaking, every embodied sensorimotor approach claims that, in intentional activities like skilful coping, perceptual and motor processes determine each other and form a loop, generating a dynamical equilibrium from which the body and the environment emerge as two virtually distinct – but always reciprocally adherent – stable entities. Also if a part of mirror neuron activity can be derived by such a homeostatic loop of compensations based on kinaesthesia and proprioception, a few evidences suggest that their functioning can’t be reduced to it, so that they exceed a purely sensorimotor frame. Wolfgang Prinz (1987, 1990, 2002, 2005), perhaps today’s most eminent advocate of the ideo-motor approach in embodied cognition, has already discussed this problem, and the experiments of his research group lead to claim that imitational abilities related to mirror functions can provide the best explanation for (and can be best explained in) the framework of motor ideas; this claim implicitly endeavours to undermine the idea that mirror neuron function amounts to a sensorimotor devices for keeping a continuous equilibrium between body and world, and consequently this challenges the hypothesis that mirror neuron circuits work like (or together 19 Quite often mirror neurons are indicated as “sensory-motor” neurons for they respond to both perception and execution tasks. An enactive account of mirror neurons is possible by stressing the sensorimotor modalities of their functioning (Sinigaglia 2008). Soon I’m going to propose that mirror neuron function can be explained either in a sensorimotor or in an ideo-motor framework. 20 This is a very basic feature of the embodied approaches to cognition: see for example the enactive approach, presented in the seminal book of Francisco Varela et al., The Embodied Mind (1991), or the Reciprocal Continuous Causation (CRC) model in Andy Clark’s Being there (1997), or Alva Noë’s claim that “perception is something we do” (Action in perception, 2005). 7 with) attractor basins devoted to extinguish the sense of deviation from a body-environment optimal gestalt. Mirror functions need also an ideo-motor approach because not always the execution/recognition of goal-oriented action is strictly motivated by perceptual stimuli, even though it is true that perception can play a contextual role in order to evoke the motor goals instantiated by mirror-neurons. What matters, here, is that mirror-neuron-based motor schemata are not triggered by a specific set of perceptual stimuli and are not guided by an on-line flow of perceptual data: thus, the sensorimotor preconditions for soliciting and for controlling intentional motor schemata are undetermined, and this is experimentally shown both in the recognition and in the execution of intentional goaloriented actions. - Regarding the recognition of the action, experiments show that the stimuli which casually activate mirror-neurons-related motor schemata are never coupled with the schemata in themselves. The stimuli can be, in facts, multimodal (for example acoustic or visual)21 or incomplete (if the action is partly hidden22); and other studies on premotor cortex show that motor circuits related to intentional actions can be activated even if the perceptual stimulus is absent (in the case of motor imagination23). In other words, it is true that one or more perceptual stimuli can trigger the activation of motor schemata, but there is no necessary specific association between perceptual stimulus and motor content. - Regarding the execution of the action, it is easy to show that the kinaesthetic and the proprioceptual feedback of the agent’s body doesn’t play almost any role during the motor performance, because when mirror neuron activity has been initiated the action was already completely configured for reaching its purpose; a sensorimotor feedback can perhaps play a role in this kind of coping in order to achieve an on-line correction of the trajectory of the movements according to some dynamic changes in the perceptual background, but this contribution offered to the action is very often almost only auxiliary, and anyway it only intervenes during the execution of the action, because it has nothing to do with the previous operations of planning, preshaping and initialization of the motor program. From the phenomenological point of view, these claims are consistent with the concepts already perfectly outlined by Sean Dorrance Kelly (2000) in his philosophical enquiry about motor intentionality. He has specifically considered the grasping behavior as the exemplar case of a motor intentional action that doesn’t require a supervisory device in order to reach its goal, because sensorimotor feedbacks are not really relevant during the execution of the movement24. But these claims can be definitely confirmed also from the empirical point of view, by means of a subtractive analysis obtained via temporary inactivation of the motor programs instantiated in premotor cortex 21 Kohler et al. (2002). 22 Umiltà et al. (2001). The sight of a partially hidden action of grasping is sufficient to trigger in an observing macaque the mirror neuron circuit corresponding to the grasp; the macaque can’t see the exact moment in which the prehension of the object is realized, but the sight of the initial part of the movement is sufficient for suggesting the goal of the action considered as a whole. 23 Jeannerod & Frak (1999). 24 This accords with the Merleau-Pontian account of grasping, quoted by Kelly “From the outset the grasping movement is magically at its completion […]”. According to Kelly, this means that “the initial intention to grasp is sufficient to ensure, in normal circumstances, that the limb will reach the appropriate end-point in the appropriate way.” (p. 176). Kelly’s account of grasping seems very well matching the description of motor intentional activity enacted by graspingrelated mirror neurons. From the point of view of a general theory of smooth coping, Kelly’s description of motor intentional actions is perfectly compatible with (and complementary to) Dreyfus’ description but, while the former stresses the specificity of grasping (in which the motor project is already given as a meaningful whole), the latter stresses motor actions involving a continuous adaptation to the environment (and this is the principle of maximal grip). Each of them uses effectively the phenomenological examples provided by Merleau-Ponty, and I think that the differences between their perspectives derive from these different choices, and not from some conceptual dissonance, since both of them are allowed by Merleau-Ponty’s phenomenology. I think this duality reveals that motor intentionality can be oriented in two opposite ways: sensorimotor (“looking at painting”) and ideo-motor (“grasping a cup”). 8 by mirror neurons and canonical neurons (and, once again, these programs concern grasping). The experiments performed by Gallese et al. (1994), and then by Fogassi et al. (2001), are specially concerned with the so-called canonical neurons of premotor cortex, which are very relevant in the present analysis because they map the same kind of motor goals which are codified by mirror neurons circuits. Mirror neurons and canonical neurons are somehow twinned, and their functions are quite alike since they instantiate the same motor “vocabulary”, but with different modalities of perceptual access: in performative tasks, both the families of neurons enable the execution of goaloriented motor actions; but in perceptual tasks, while mirror neurons respond only to the sight of goal-oriented actions, canonical neurons respond only to the sight of objects presenting a morphological structure that is prominently available for performing such actions (so, for example, the observed handle of a coffee cup results salient for the activation of “precision grasp”-type canonical neurons)25. The experiments have shown that if muscimol microinjections temporarily inhibit some groups of canonical neurons involved in the modelling of precision prehension, in monkey’s F5 zone, the execution of the prehension results seriously uncoordinated, as if the monkey had been deprived of the general understanding of the intentional meaning of the action. The monkey does not succeed in pre-shaping, through a simple observation of the object, the necessary movements to perform the finalised action, which now requires “a series of corrections made under tactile control” (Fogassi et al. 2001); the movement of the monkey needs repeated explorative movements in order to reconstruct the correct motor schema and hence conclude the precision grasp. The chemical intervention did not jeopardise the ability to reconstruct the sensorimotor morphology and the trajectory of coping activity. The monkey didn’t forget what is the structure of the movement, but how to act in accordance with a goal. What is missing then is not a series of kinaesthetic invariants, but a general practical schema for the goal of the action, a schema which would include the pragmatical meaning of the movements and that at the same time would motivate them and control them.26 These experimental facts are consistent with the phenomenological assumption that intentional action is a holistic experience: even if the motor schema is solicited by a perceptual act – there is no series of perceptual contents that, regarded by themselves, could be considered responsible for the activation of the execution/recognition of the action, because merely perceptual data – extracted from their pragmatical context - don’t carry the kind of significance that can be relevant in order to elicit a motor-intentional attitude. In other words, contingent perceptual contents can offer nothing more than minimal cues that are strictly sufficient for enabling the execution/recognition of the action, but no perceptual structure taken in itself can determine the comprehension of an action that is fully matching the pragmatical situation. Perceptual stimuli, at best, can represent casual occasions for eliciting the access to goal-oriented motor schemes, but no specific perceptual stimulus has to be constantly associated or causally related to the meaning of the action. This is necessarily true because, as I have already pointed out, mirror neurons, canonical neurons, and premotor cortex in general, express motor competences and not perceptual competences, and moreover the motor competences are expressed as meaningful wholes, and not as combinations of discrete parts. This point offers a new light for interpreting some studies on imitation, which can be useful for confirming that “imitation involves a direct mapping of a non-decomposed action pattern” (Bekkering et al. 2000); normally, imitation is not directed to the reproduction of the single perceived components of the movements, but to the meaningful purposeful intentions that tells us “how to behave for” achieving a goal. In facts, motor programs do not respond to the perceptual stimulus in itself: besides of insignificant perceptuali stimuli, there should exist some unitarily structured pragmatical meaning that belongs to the whole context and that holistically underlies the casual perceptual contents; this structured pragmatical meaning is evidently embedded in the body25 “Thus, the visuomotor coupling shown by canonical neurons could be at the basis of the sensorimotor transformation that adapt the hand to a given object. The visuomotor discharge that characterize mirror neurons could be at the basis of action imitation and action understanding” (Fadiga et al 2000, p. 175). 26 Binkofski et al. (1999) offer confirmations of this claim within the frame of clinical neuropsicology. 9 background link and offers to perceptual stimuli a context that makes them significant and affordable as if they carried sufficient motivations for action execution or recognition. These observations confirm that the goal of the action is a motor goal: an embodied, and primarily comprehended practical project27 in which the perceptual stimuli are consequently introduced; a project that is much more relevant than the perceptual content of the stimulus in itself. Dreyfus himself28 has often pointed out that the goal of coping is evoked by its context of meaning, while the perceptual stimuli – extracted from their background – have no meaning at all. From the point of view of motor intentional activity, motor goals and pragmatical contexts are closely connected and together they shape the form of the intentional action before and below any sensorimotor exploration of the environment; for this reason, the content of perceptual stimuli is accidental and even secondary since it is always already filtered by the incoming goal-oriented scheme of motor intentionality. Harmonization between body and world, as it is enacted by mirror-neuron-based coping, doesn’t take place through a progressive refinement of a sensorimotor balance; and this is radically different from what happens, for example, in the case of a man assuming the best position for looking at a painting in a museum. Andy Clark (2001) had already pointed out that the bounds between conscious visual experience and motor action can become “too tight” if the whole activity of skilful coping is reduced to an adaptive sensorimotor process29. In facts, in many merely reactive processes of skilful coping, there must exist something more, besides the perceptual stimuli, in order to motivate the action: not a plan or a representation, but what seems to be an idea, belonging to a realm of experience that Merleau-Ponty would have defined invisible; not some intellectual content behind or above the action, but a sort of meaningful depth of the motor experience that provides the action itself with an organic pragmatical shape, and that embeds each perceived stimulus in its holistic intentional context; an ideo-motor schema, capable of motivating the goal-oriented action even when perception is neither sufficient, nor relevant, nor present. I will now sketch the main concepts underlying the ideo-motor approach to intentional actions; later, I will point out how it differs from the sensorimotor approach and I will then propose that their relationship can be better understood in the framework of the embodied approach to cognition; then, I will specify that also the ideo-motor approach to goal-oriented action is unable to capture the specifity of motor intentionality enacted by mirror neuron functions; finally, I will argue that a mirror-neuron-based theory of motor intentionality can be better understood only if it is considered as a key function capable of mediating the sensorimotor and the ideo-motor processes. Ideo-motor action, imitation and mirror neurons In The Principles of Psychology (1890, p. 526), William James has proposed a very famous and lasting description of ideo-motor action: he wrote about the tormented experience of getting out of 27 I intend the concept of “project” in a Merleau-Pontian sense, as “a motor project” or “Bewegungsentwurf” (MerleauPonty 1962, p. 144): not a design, or a plan of intervention, but a sort of meaningful being-directed-toward. 28 For example in Dreyfus (2008), p. 348: “how can such senseless physical stimulation be experienced directly as significant? All generally accepted neuro-models fail to help, even when they talk of dynamic coupling, since they still accept the basic Cartesian model”. Wouldn’t this be true also for an account of coping restricted only to sensorimotor processes, since - namely - the sensorimotor approach is Cartesian in its very origin and based only on physical stimuli? 29 In order to explain a consistent part of our every day motor activities which are not guided by visual experience, Clark has stressed the existence of off-line memory-based cognitive processes situated between perception and motion. My analysis follows the same instance of broadening the scenery of intentional motor actions, but I will explore the possibility that skilful coping can be governed by some non-perceptual process that is, however, non-representational as well. I will argue that this process is not necessarily guided by higher cognitive processes (like memory or decision making procedures); instead, according to mirror neuron theory, it is rooted in the very intentional structure of fully embodied functions. I will hence conclude that the intentionality of motor action is neither rooted in visual experience, nor in abstract memory, nor in motor-ideas, but in motor experience itself. 10 bed “on a freezing morning in a room without a fire”. According to James, in such circumstances the idea of getting out of bed is inhibited by the ideas of the nice warmth under the blankets and of the unpleasant cold outside, in the room; a competition between these ideas goes on until when a “fortunate lapse of consciousness occurs” and “we forget both the warmth and the cold”; that’s why we “get up without any struggle or decision at all. We suddenly find that we have got up”. This could happen because the competing ideas “which paralyzed our activity […] kept our idea of rising in the condition of wish and not of will. The moment these inhibitory ideas ceased, the original idea exerted its effects.” Ideo-motor action occurs without any rational decision, not even an unconscious one: the rough confrontation between competing motor ideas, in facts, obeys neither a rational device nor a representational decision-making procedure ruled by a set of rules, and it only follows the quantitative dynamic of strengthening/weakening of basic pulses. Even if often James – in accordance with the language of his age – uses a mentalistic vocabulary for describing them, motor ideas are not necessarily mental representations in the cognitivistic sense, because they don’t really need to denote anything; rather, they promote the instantiation of motor opportunities. That’s why, in principle, there doesn’t exist any distinction between contemplating a motor idea and enacting its motor content30: the content of a motor idea is not something that stands for in front of us or inside us, it is something to do. For this reason, as stated by James, “we think the act, and it is done; and that is all that introspection tells us of the matter” (1890, p. 522). Ideo-motor action is based on three principles: the first one states that a motor idea is structured as a meaningful whole, and that its intentional content consists in its expected kinaesthetical consequences; the second one affirms that a motor idea is intrinsically motivating the action, so that thinking a motor idea means already being moving; the third one specifies that the ideo-motor action occurs when an equilibrium between competing motor ideas is broken. The first principle corresponds to the pragmatist assertion of the priority of the goal over the movements: a motor idea concretely embodies the meaning of a goal that shapes and guides all the underlying movements, without being reducible to them. When an ideo-motor-based skilful coping process is initiated, the action expresses and articulates organically, through the body, its intentional meaning, and this happens since the very first stages of the movement, because the action is preshaped from its commencement in accordance with its expected motor effects. This could perhaps explain why, as experiments on mirror neurons have clearly displayed (Umiltà et al. 2001), the practical purpose of a performed action is recognizable even if only the initial part of the movement is visible to the observer; incompleteness of the perceptual stimuli doesn’t preclude the recognition of the goal of the action, since each portion of the action can be sufficient in order to organically manifest the meaningful totality of its expected practical effects. The second principle explains why simple intentional actions are elicited and organically guided by a project of intervention in the world that is pre-reflective but already structured and pragmatically meaningful; this project is not only a cognitive structure or a meaningful content, but it is also an internal force intrinsically soliciting the action, so that the execution of the bodily movement is effectively triggered by the idea of the motor purpose embedded into the acting body itself. Research on imitation constitutes the main field for applying this principle of ideo-motor action to 30 I desume from this principle that a motor idea is not a mental representation of a motor program, but consists in what Gallese (2005) has called an embodied simulation of a motor experience, i.e. an off-line disposition of our body to prompt virtual and readily organized reactions as if a stimulus had actually induced them. According to James’ perspective, the only difference between an effectively executed action and a simulated motor idea is just that only the second one is inhibited. This hypothesis has been confirmed by the account of hemiplegic-anosognosic patients (Spinazzola et al. 2008) after being asked to perform actions that were impossible to them: the body absorbed in the simulation of a motor idea is effectively ready to perceive the sensorimotor effects of the actions even when the movement has only been planned, so that when (and if) the real movements occur, the perceptual feed-back can be considered nothing more than a confirmation of the expected feedbacks that were already anticipated by motor ideas (see Haggard 2005 for a conceptual discussion of this point). 11 today’s cognitive science: before Wolfgang Prinz, Anthony Greenwald (1970) had already stressed the ideo-motor nature of imitational processes by pointing out that, when primary imitation occurs, there must exist an experiential acquaintance between the motor schemata accessed by the imitator and the ones already frequented by the imitated one; this is a consequence of the fact that their socially shared experiences have provided them with the same motor ideas, ready for being exploited in a performative or in a perceptual way31. These two modes are then reversible, as we have already seen with mirror neurons. Greenwald has defined this reversibility and its role in imitation by referring to a “principle of ideomotor compatibility”: since the schema underlying the observed and the executable actions is the same, the process of imitation turns out familiar and without any complex elaboration. I can imitate better the movements that already belong to my motor repertoire because, when I see someone performing an action that is habitual to me, the motor idea I have accessed perceptually – by the only fact that it has been accessed – is immediately transformed into a potential performative motor command. Moreover, motor ideas are intrinsically motivating the action, and this explains why, if the imitational process were not inhibited, a subject would immediately start imitating all the movements he sees, in a compulsory way: this happens outstandingly in cases of echopraxic patients32, but – concerning non-pathological conditions – the compulsive role of motor ideas can explain a relevant component of the imitational attitudes in early infancy, which constitutes the support for behavioural learning in many mammal species, and notably in humans. But then, if a motor idea is activated by the simple perception of the other’s action, and if it is true that it is intrinsically motivating, why people are not compulsively imitating each other all the time? The third principle of ideo-motor action answers this question. James proposed the concept of ideomotor action in order to explain a particular kind of voluntary movements that are motivated only by the ideas present “in the mind” of one subject, independently from what he feels or perceives. In our consciousness, according to Jamesian model, different motor ideas are continuously competing with each other; most of the time this competition brings to inaction, because the different motor ideas counterbalance each other and mutually annihilate their effects; but it continuously happens that one motor idea gets stronger than the other ones, activating effectively the related motor schemata and eliciting then an effective action. One motor idea can overcome the other ones and trigger the execution of the bodily action because it has been suddenly strengthened in a salient way (by an emotion, or by a thought, or by sensorial stimuli), or because the competing motor ideas became weaker and started fading away; action results, in both cases, by the breakup of an existing dynamical balance. What mirror neurons experiments show, underpinning a thesis that has already been developed in imitation studies, is that one subject’s motor idea inherent a certain kind of intentional action is elicited to a certain extent when he observes the same kind of purposeful action executed by someone else in front him. It has been suggested that mirror neurons play an important role in imitational attitudes, with different degrees in monkeys and in humans. According to Wohlschläger and Bekkering (2002), it is “very likely that imitation emerged from the mirrorneurone system of the common ancestor of monkeys and humans.” If mirror neurons mediate the imitation process, then, how imitation may not occur despite of mirror neurons, since they are always elicited by the perceived transitive actions of the other agents? Most of the times, the elicitation of a motor idea in the observing subject is not strong enough to overcome the other motor ideas present to his consciousness, and this means that the observing subject can have a weak access to motor schemata without effectively initiating the imitation of the observed action (the association between imitational ability and motor facilitation can be experimentally shown by motor evoked potentials in TMS studies, see Léonard and Tremblay 2006). But, in some cases, the observation is enough for compelling the effective execution of the 31 This is confirmed by fMRI studies on mirror functions activated in expert dancers while looking at videos with familiar dance movements (Calvo-Merino et al. 2005). 32 See Pridmore et al. (2008) for a mirror-neuron-based account of echopraxia. 12 associated motor scheme, and in this case imitation occurs. It is a contagion-like form of primary passive imitation directed toward the motor intention, and not the movements: motor schemata triggered by mirror neuron activation are always goal-oriented, and this means that what the subject is actually imitating is the goal – the intentional content of the action - and not the mere observed movements. That’s why children, during the first year of life, imitate more easily actions that are salient also (or mainly) for their effects, and not only for their mere movements (Elsner 2007), and in 4-5 years old children imitation is explicitly goal-directed (Bekkering et al. 2000). Also experiments on ideo-motor apraxic patients have provided “new support for the goal-directed theory of imitation”, by showing that – in accordance with the ideo-motor principle - “an observed action is represented as a set of goals (possible action effects) that activates the motor programs that are most strongly associated with those goals.” (Bekkering et al. 2005, p. 429). The Jamesian theoretical device based on competing motor ideas seems compatible with the empirical data on mirror neurons, though the experiments can’t completely validate this model at the moment (there are no evidences of reciprocally competing mirror neuron circuits): but it is true that mirror neuron activation, if not inhibited by some supervising neural device, can be involved in the automatic initialization of an action. In any case, even if we could demonstrate that the Jamesian-like motor ideas were completely implemented in mirror neurons, this model would still leave space for other neuronal and functional devices, since probably it would be too simplistic to affirm that the whole decision making process undergoing the activation of a motor scheme is mechanically compelled by a “plus-minus” system of conflicting motor instances. Even though, as Greenwald and Prinz have suggested, the ideo-motor model reveals its strength when it is necessary to account for sudden, spontaneous, unprepared, compelling and possibly contagious motor experiences. Where do motor ideas come from? In many situations they are evoked33 by perceptual stimuli emerging from the environment (or by affordances provided by the surrounding objects), and this seems immediately consistent with a sensorimotor account of the embodied action (as it has been described before); but in most cases motor ideas are just popping up from the personal stream of consciousness of the subject, without any relevant influence coming from the environmental cues or from what the body feels (and this is what probably happened to a lazy William James laying in his bed, as he was more paralyzed by the idea of the cold room than by the cold itself). This important case seems not to be accounted for by the sensorimotor approach, and we need to clarify it in order to understand if the concept of ideo-motor action is compatible with an enactive approach to motricity. Rethinking the ideo-motor approach within the frame of motor intentionality The sensorimotor account of skilful coping and the ideo-motor one seem alike because both of them are available for a non-representationalist embodied account of motor experience: in both cases the acting body is endowed with a motor intelligence that is able to express/comprehend the purposeful meaning of the intentional action before and below any higher level of the cognitive processes. Within the sensorimotor account, the acting body possesses a pre-reflective intelligence, in the sense developed by Merleau-Ponty; but, in its peculiar way, the ideo-motor action is intelligent and pre-reflective as well, according to James, for the motor ideas can be transformed into real actions without the agent having developed a plan for making this happen. Ideo-motor action occurs as a purposeful intervention in the world, but it happens without any deliberation and without a plan. Both ideo-motor action and sensorimotor action can explain intelligent, goal-oriented intentional actions by referring only to the motor inclinations deep-rooted in bodily experience, and in this 33 Ideo-motor actions are evoked, indeed, and not mechanically provoked, since (again) this would be the case of a sensorimotor process mechanically elicited by perceptual stimuli. 13 sense both of them can account for some kind of skilful coping34. But differences are more remarkable than similarities: the two kinds of account seem so distant because only the former conceives the intentional action as a progressively defined schema of movements embedded in the perceptual situation, while the second one conceives the action as an already-there motor program that is embodied though virtually independent from the actual perceptual content. Considered in the framework of classical psychology, sensorimotor approach and ideo-motor approach appear perfectly complementary because each one excludes the other possibility, and at the same time it seems there isn’t a third possibility: the former, revealing its far Cartesian ascendancy35, describes how the action is motivated by the stimuli offered by the perceptual environment, while the latter describes how it can be motivated by intentions that are originated in non-perceptual consciousness. The first one assumes that the action starts from the “external world”, and the latter that it starts from the internal realm of consciousness; evidently this distinction presupposes a sharp dualism between the external objectivity of perceptual data and the internal subjectivity of mental contents. This dualism is supported by the old-fashioned empiristic framework of classical cognitivism, according to which motor-ideas are just off-line stored representations of sensorimotor schemata that have previously been acquired on-line as perceptual representations. I would like to explore the possibility that sensorimotor and ideo-motor account for embodied intelligence can be better integrated if they are considered in a more comprehensive nonrepresentational conceptual framework inspired by the embodied/embedded theories of cognition; in facts, in an embodied framework, internal and external experiences exist as parts of a systemic process that enacts at once the mental reality of the subject and the environmental world; internal processes and external world don’t exist separately in themselves but are enacted reciprocally in a continuous process of dynamic coupling and mutual causation. In this new framework, sensorimotor and ideo-motor stimuli for action appear to draw a sort of circle, since intentional behaviour can be anticipated by its expected sensory feed-back, and perceptuali stimuli can be anticipated by their associated motor goal.36 The output anticipated by each one of the two systems can be put at work as the informational base of inputs for the other system. I will show soon how experimental studies on motor skills (and particularly on mirror neurons) can suggest that these two anticipatory experiences are not only symmetrical (because they present an inverted scheme), but also contiguous (because it seems they participate to the same general process of constitution of the margins between self and environment), and quite often morphing into each other, so that their relationship of reciprocal inclusion must be re-defined under a new profile of 34 This is possible in accordance with the oldest ideo-motor doctrine: William Carpenter (1852) identified ideo-motor actions as a third category of nonconscious, instinctive behavior, which also included excitomotor (breathing and swallowing) and sensorimotor (startle reactions, as for a slamming door) activity. 35 Hommel et al. (2001, p. 855) stress the Cartesian ascendency of the sensorimotor approach in classical psychology, but it should be noted that the Jamesian ideo-motor approach, if it is conceived as a mental device of representation, is nonetheless dualistic. I suppose that the only way to overcome the dualism underlying the sensorimotor and the ideomotor approach is to ascertain their reciprocity and continuity in a circular body-environment constitutive process of enaction defined by a wide notion of motor intentionality. 36 Elsner et al. (2002, p. 364): “Like sensorimotor mapping, ideomotor learning consists in acquiring a consistent relationship between a motor event and a sensory event, and it is likely that both types of learning rely on associative learning mechanisms integrating events that frequently occur in close temporal succession. However, ideomotor and sensorimotor learning tap different aspects of the learning situation. By sensorimotor mapping, people learn associations between cueing stimuli and subsequent actions, whereas by ideomotor learning, they acquire associations between actions and subsequent sensory events (i.e., perceived action effects). Thus, when playing the piano, both types of learning may be present, but sensorimotor mapping would associate the finger movement to the sight of the note, whereas ideomotor learning would associate the finger movement to the hearing of the tone. Moreover, the two types of learning serve different behavioral functions: while sensorimotor mapping helps to adapt behavior to the environment (Kurata et al., 2000), ideomotor learning helps to adapt behavior to the agent’s intentions. Indeed, without learning associations between actions and their consequences, agents are unable to plan a movement that is appropriate to achieve a desired action goal.” 14 complementarity: since motor schemata and perceptual schemata can be immediately reversible and mapped into each other, their specific domains of application are partly overlapping and have lost many of their boundaries. We can clearly see that the dualistic ontology underlying the old distinction between sensorimotor and ideo-motor is collapsing, and the definitions of the two processes feature a more and more ambiguous identity in the concerned psychological literature. For example, I consider notable that Wolfgang Prinz and his collegues37, by endorsing their ideomotor account for imitation, impute to sensorimotor theory a dependency from a stimuluscognition-response mechanicist device, while enactive sensorimotor theorists like Susan Hurley (1998) had already imputed the simplicity of this sandwich-like scheme to classical cognitivism. It seems that the renewed sensorimotor theory and the renewed ideo-motor theory are both paying efforts for overcoming this old linear scheme, and they move from different starting points toward a common unified embodied framework38. I would like to explore the possibility that, in the Merleau-Pontian framework of motor intentionality described by Dreyfus39, or in a frame of embodied cognitive science (like the one originary proposed by Varela et al. 1991), the sensorimotor account and the ideo-motor account can be possibly unified since each of them (as I’m going to make clearer soon) describes a dynamics that belongs to the same basic process of re-modulation of the boundaries between body and world, even if they identify two different directions in which the tension driven by motor intentionality flows; this perspective seems attractive because it would distinguish how both of them are implicated in skilful coping and in simple goal-oriented actions like the ones enacted by mirror neurons. In accordance with a coherent interpretation of the embodied approach to cognition, my main hypothesis is that a non-dualistic definition of the distinction between sensorimotor and ideomotor can be put at work both on the phenomenological and on the empirical level. In facts, at the phenomenological level, the distinction between sensorimotor and ideo-motor amounts to a distinction between a process of relaxation and a process of explosive increase of the tension of the bodily situation toward the environment; on the empirical level, the same distinction amounts to a difference between a bottom-up and top-down process for modelling motor intentions and goals. Within these definitions, sensorimotricity and motor ideas don’t amount anymore to two distinct domains of stimuli (environment vs. mind, external vs. internal), but they amount to two different ways of enacting bodily experiences in a common systemic loop of embodied and intentional processes. These new unified definitions might have some consequences for the classical approach to cognition, because they show that the old-fashioned framework can be overcome not only for what concerns the sensorimotor process, but also for the ideo-motor process. This is relevant because – until now – the latter has been assumed as preeminently “mental”, while there exists at last one way for describing it too in a non-representational fashion or, at least, in a quasirepresentational fashion that is very much different from the one propagated by classical cognitivism. These definitions might have consequences also for the embodied approach to cognition, because they show that the enaction theory can and must extends itself beyond the simple sensorimotor coupling, by reaching the territories of intentional non-perceptually motivated/controlled agency. From the phenomenological point of view: ideo-motor action breaks the gestaltic equilibrium 37 See Hommel et al. (2001, p. 855): “In the sensorimotor view of action, actions are regarded as ‘reactions’, that is, as responses triggered by stimuli.” 38 Studies on concurrence between perception and action show that “both sensorimotor-adjustment and activationinhibition accounts seem to provide viable explanations” (Grosjean et al. 2008). 39 Merleau-Ponty’s analisis of motor intentionality, in facts, doesn’t have to be reduced necessarily to a sensorimotor account of coping, since coping is not instantiated only via kinesthetic variations; and Dreyfus’ model of the intentional arc can be expressed in more general terms too, since it pertains to the widest possibility of adaptive association between self and world. 15 When I perform skilful coping, according to an embodied sensorimotor approach, I know how to act because each perceptual situation offers an open-ended set of Gibsonian affordances (sensorimotor opportunities for movements), and – at the same time - because the execution of each series of movements is associated to the expectation of its motor effects (constituting an approximation of the “motor-goal” of the action). Ideo-motor account of skilful coping is different because it tries to explain how the action is possible even when the perceptual situation and the proprioceptual feedback is not relevant. In many situations we start acting even if the environment doesn’t offer any specific affordance that would motivate it (this happens for example when we are thoughtful or absorbed in some introspective activity). Sensorimotor account of coping describes how it is possible to act by responding to the environmental calls; ideo-motor account described how it is possible to act despite the influence (real or just expected) of the environment. Skilful coping, as it has been effectively synthesised in Hubert Dreyfus’ sensorimotor description of intentional action, is a process that tends to extinguish the sense of deviation from an optimal gestalt; this gestalt constitutes the expectation of a perfect equilibrium between body and environment, a situation that can be said to have been reached when we don’t need anymore to act in order to overcome the sense of tension. But, on the other hand, it is necessary to account for that kind of coping that goes exactly in the opposite direction, because it tends to break the equilibrium in which, apparently, action is not anymore required by the environment. Dreyfus himself (2002b, p. 418) seems to implicitly acknowledge this necessity, while discussing his own theoretical account of skilful coping: motor intentionality is continuously in play as we move to get a maximal grip on our world, so that the flow of coping needs only rarely to be initiated from scratch. (Perhaps, when we will to get out of bed in the morning and begin our day). The tendency toward getting a maximum grip on the world is all the intentional context that is required. The example used by Dreyfus into brackets is striking because it is the same described by James in his very famous account of ideo-motor action. Merleau-Pontian motor intentionality seems to be a continuous and endless process, but we must admit at least some interruption, or some change of direction, during its course, because otherwise we couldn’t explain how we could ever escape from the situation of stillness corresponding to the satisfactory gestalt, once we have reached it: sometime and somehow we must get out of bed, and this requires to break the enchantment in which we are prisoner; we must then create a tension between what the environment suggests to our body and what the body is required to do. This is conceptually allowed by the fact that, if the distance between the self and its optimal gestalt can be reduced in skilful coping, then there is no reason why it couldn’t be also incremented. It is not obvious that coping could be initiated from scratch “only rarely”, because our every day experience suggests that endless times our actions start literally from nothing. This is not only an empirical issue about the frequency of the actions initiated from scratch, but reflects a more radical phenomenological point: normally we can distinguish intentional actions from non-intentional movements just because quite often the former, and surely not the latter, manifest the phenomenology of intrinsically motivated acts (which are indeed started from nothing that could mechanically produce them from the world); and even if it were true that rarely we did initiate actions from scratch, it seems however necessary to clearly understand how this interruption, or intentional delay, in the flow of coping is phenomenologically possible (with a consequent new commencement for coping activity). A new start is indeed possible because in many occasions of our daily life we experience that the perceptual content of our bodily condition simply doesn’t matter or must be even ignored; and sometime we experience a state of perfect peace, in which the perceptual stimuli are so monotonous and feeble that they can’t solicit any response: what happens to motor intentionality in these 16 cases?40 In order to answer this question, it is maybe necessary to introduce a second principle for complementing Dreyfusian motor intentionality: in facts, why and how do we continuously break the body-environment equilibrium we have reached? A purely sensorimotor account of skilful coping doesn’t really explain it, since it only describes the process aiming to this equilibrium41. Of course it is possible to argue that every movement of coping directed to extinguish the sense of deviation from the optimal gestalt generates a non-controllable reaction which produces an opposite non-balanced effect, so that a new sense of deviation is engendered and new coping motivates the search for the equilibrium42; this explanation seems convincing, and probably it would be also sufficient if we could continuously maintain a perfect adherence to the perceptual situation of the environment. But of course it is not like this, because the adherence instantiated by the intentional 40 Dreyfus offers a possible answer by postulating that (almost?) every situation of apparent peace is in reality traversed by an interior, invisible tension that we don’t notice because it is continuously extinguished while it is produced: the equilibrium is dynamical in such a case, because the sense of distress produced by the environment is dispatched exactly with the same rate it is produced. “If it seems that much of the time we don’t experience any such pull, Merleau-Ponty would no doubt respond that the sensitivity to deviation is nonetheless guiding one’s coping […]. The absence of a felt tension in perception doesn’t mean we aren’t being directed by a solecitation.” (Dreyfus 2008, p. 343). I’m not sure this explanation could be always phenomenologically convincing, at least not in the local sense of specifically goal-oriented actions: when I’m simply not acting I don’t have any feeling of being involved in the process of dispatching an environmental call, and I don’t need to suppose such a redundant device (rather, it is true that, as in Jamesian account, when I’m paralyzed by the competition of different ideas, I can really notice the sense of distress generated by their invisible tension). Is it not easier to admit, by applying Ockham’s razor, that skilful coping is not always generated by the environment and that there exists one more way of executing embodied intelligent actions? And, in any case, it should be explained why we are very much disposable to recognize as intentional the experience of self moving without being elicited by anything, while the more an action is motivated by the external context, the more we are disposed to recognize it as an unintentional, mechanically generated movement. This is what normally makes the difference between an animal and a puppet, but how to describe this difference in Dreyfus’ account? This question resonates, in part, with the objection already directed by Louise M. Antony toward the Merleau-Pontian example of the “soap bubble”, (2002, p. 398), but I believe the answer to my question would now require a specific characterization of inaction in an intentional context. 41 Of course the discussion of this point should be more sophisticated than the rapid sketch I have proposed here: I believe that skilful coping, in Dreyfus’ theory, doesn’t explain how it is possible to “start from scratch”, but on the other hand it is true that Dreyfus’ doctrine of motor intentionality, in accordance with Merleau-Ponty’s and Heidegger’s phenomenology, is deeper than a theory of cognitive processes and applies to a wider existential landscape. It is not only a theory of local goals which come under the spotlight during skilful coping; in facts it contemplates also a background coping activity; while skilful coping is involved in local contexts and in actions oriented toward definite goals, background coping is concerned with the widest contextuality of action, and coincide with the global existential situation of the agent. Background coping is not thematically focused on specific goals, but consists in a modulation of the totality of the intentional life of the agent; its attractor basin is not defined by some particular modalities of caring, but consists in the very situation of being-in-the-world. In this sense, motor intentionality considered in his most holistic context is already effectively described by Dreyfus’ general theory of coping; this part of the theory seems to me already complete, because it testifies the continuous co-dependency between the Dasein and his background. But since my claim concern specifically the locally goal-oriented actions (corresponding to mirror neurons vocabulary, or to a definite set of attractor basins), I find necessary to acknowledge that a purely sensorimotor account of skilful coping is not sufficient, and that it is open also to the ideo-motor processes. I believe this thesis doesn’t change the global hermeneutical framework of Dreyfus’ theory, but articulates a distinction inside it, which is made necessary by the fact that every description of coping offered until now amounts to sensorimotor-only processes. Globally, then, the existence of the embodied agent amounts to a process of continuous adaption (and co-constitution) between body and world; but it seems that, locally, motor intentionality must be expressed both through a sensorimotor adjustment (according to which the behavior of the agent is invited to adapt to his environment) and through an ideo-motor adjustment (according to which the environment is forced to adapt to the intentions of the agent). 42 “Equilibrium is Merleau-Ponty’s name for the zero gradient of steady successful coping […]. Normally we do not arrive at equilibrium and stop there but are immediately taken over by a new solicitation.” (Dreyfus 2008, p. 343). But what would happen, then, if the equilibrium were effectively reached, since this possibility can never be excluded? And how could we escape this equilibrium in the case no solicitations from the environment pull us to do it, since also this possibility can’t be excluded? I believe Merleau-Ponty’s account can offer a solution to this problem if we include ideomotor activity in the flow of motor intentionality directed to coping. This means that motor ideas must also be considered as active forces which are able to re-draw the landscape of intentional arc at any moment by creating new situations of tension and new ways of exploiting attractor basins. 17 arc is very often delayed, broken, or just started from nothing perceptually relevant. Cognitivism (or “intellectualism”) would endeavour to answer providing a different explanation. Every classical cognitivist would actually confront this question by claiming that we can break the quiet state of the body-enviroment situation because representations allow it. Motor programs are represented somewhere and somehow as sets of rules and are always accessible in order to instantiates new movements, even if the environment doesn’t offer any affordance that would motivate it. In reality, this claim doesn’t answer our question, since we are specifically considering coping, i.e. a pre-reflective and non-representational (but still intelligent) bodily activity; nothing concerned with complex mental devices as plans, models, concepts, beliefs, propositional attitudes, comparison capacities and so on. On the contrary, the ideo-motor approach to motor intentionality can perhaps provide an answer to the question: in facts, it explains how we start acting even if this means to break the situation of equilibrium established by our body toward the environment. Motor intentionality engendered by motor ideas instantiates motor goals within a process that is not necessarily aiming to the extinction of the body-environment tension, but possibly to the explosion of such a tension. According to James, this can happen because of the energy embedded into our ideas; a force able to motivate our movements for the very fact that a movement has been conceived. The body expresses this energy when one motor idea overcomes the other ones and breaks the optimal bodily equilibrium: the intentional movement underlying this process is the essence of the goal-oriented content that motivates ideo-motor actions. It is remarkable that, in the case of Dreyfus’ skilful coping, according to Freeman’s model, the energy passively falls into the neuronal basin related to an intentional action according to the stimuli captured on-line from the environment; the action emerges while a chaotic process gradually finds its own state order, by reaching its minimal possible level of statistical disorganisation; on the contrary, in the case of James’ ideo-motor action, if a new order is found at the end of the action, it is probably because some energy has been actively supplied by the most vivid contents of off-line consciousness in order to break the previous order established in the attractor basin’s concavity. We can metaphorically represent this process by imagining that the attractor basin is filled up and even exceed by the sudden increase of neuronal energy (but, in reality, a functional neuronal model is missing for representing this dynamics, and providing it is not among the purposes of this article). In both cases, the repositioning of a certain amount of energy expresses the purpose of instantiating the potential of motor intentionality; according to this model, then, stillness is the situation in which the action doesn’t need to be executed because the energy is maximally stable and can keep itself into its own intrinsic equilibrium as mere potentiality for some further expressions of motor intentionality. From the empirical point of view: sensorimotor action captures regularities in kinaesthetic variations, while ideo-motor action offers a top-down guide for goal-oriented motor programs According to the pragmatist principle asserted before, the purpose of the action is not produced as a mechanical consequence of the movement or as an abstract pattern inducted from the kinematics, but is prefigured at the beginning of the action itself; by engendering the action, the motor purpose is not only the occasion motivating its commencement, but it works also like a norm modelling the action and giving it a purposeful shape while it is executed. The ideo-motor norm doesn’t consist in an objective, abstract representation of the outcome of the action or in a set of rules determining the movements, and rather it consists in a subjective, situated teleological mode of carrying out the process of planning and executing the action itself. Under this respect, it looks very similar to an inverted version of the satisfactory gestalt engendering sensorimotor skilful coping: it works like a 18 norm for the action, but it is not, in any case, a representation of it.43 James’ idea, as underlined by Prinz, seems remarkable because it does undermine the sensorimotor presumption that the goal of the action is necessarily a bottom-up product of the kinematic morphology of the moving body parts, as if – before being moved, or before having perceived the movement – the body couldn’t possess any concrete intelligence of the motor effects it is going to produce. The ready availability of motor ideas suggests that the goal of the action is not necessarily a scheme of invariants empirically extracted by the sequence of movements involving bodily components: in order to model the form of motor goals, embodied cognition is not compelled to work linearly by means of a progressive composition of kinaesthetic data, as these data are not really essential for planning/understanding actions that have already been shaped in a purposeful way.According to the ideo-motor account of skilful coping, the intentional meaning of the action is not reducible to the sum of the body parts involved and of their topological modifications in time. As mirror neurons studies have shown, when an agent performs skilful coping, the action is not continuously shaped by the proprioceptive data informing the agent of what his body feels or looks like, because – according to Greenwald (1970, p. 91) – this adaptive process would take too long in many situations where a much “faster” and “cruder” realization of the action is preferable. In ideo-motor action this mode of realization is possible because, even before being initialized, the scheme of the movements was already shaped in accordance to its motor goal, in a way that is blind to the perceptual context; on the other hand, when an agent recognizes the intentional meaning of a performed ideo-motor action, he doesn’t need to combine mechanically the series of perceptual data concerning the kinematics of the moved body parts, because the recognition can successfully occur when perceptual data are incomplete or even unexpectedly new (for example if an unexpected effector is involved in the action, or if the effector follows a completely new trajectory). In all these cases what matters the most, in order to access the right comprehension of the action, is not the perceptual experience of the produced movement, but the already-given idea of the expected goal, suggested by some minimal cues in the holistic structure of the observed action. Studies on imitation (Elsner 2002), help us again to see how the sensorimotor process and the ideomotor process represent two symmetrical sides of the same general context-adaptive process controlled by motor intentionality. Sensorimotor process tells how the body should behave in order to adapt to the environment; ideo-motor process predicts how the environment will change for adapting to the acting body. The former modulates the kinesthethic data for anticipating motor effects that will possibly produce an intentional goal; the latter uses the already-familiar idea of the goal for anticipating the motor effects that will be necessary in order to modulate the kinaesthetic activity. It is possible to summarize the past descriptive analysis within this table: Embodied intelligence: two directions for motor intentionality44 43 In the past, the teleological principle embedded in ideo-motor theory has been strongly contested by who, like Thorndike (1915), wanted to defend a purely mechanistic account of action execution; but today, the teleological direction of the action is considered a basic feature of the phenomenology of living systems, and the anticipatoryprotentive models of motor activity are widely accepted, representing the basis for every phenomenologically consistent cognitive scienceI would like to mention the importance of anticipatory processes in Alain Berthoz’ theory of protension in motor systems (see Berthoz 1997), but also feed-forward functions of mirror neurons during the anticipation of the structured motor chains (Fogassi et al 2005). 44 Many of the distinctions presented in this table derive from an interpretation of Hommel et al. 2001. This table is also compatible with other theoretical concepts involving the same kind of distinctions (references are in the next footnotes). 19 Удалено: ¶ Sensorimotor From stimuli to intentional response Motor intentional process Direction of association The action must adapt to the world Familiarity toward kinaesthetic schemes anticipates the idea of the goals achievable by the action Process Kind of goal Expectations Postdictive: extracts, similarly by pretence, mental states that produced an observed action ("What goal would make me do this?") Comprehension (simulation strategy)45 Inverse model (controller): produces the motor commands that are appropriate to accomplish a desired end state Control46 Experience teaches how behaviour can be adapted to the environment Imitative learning: acquiring the means for acting leads to get to the goal Observation of single movements triggers the execution of the related simple (decomposed) motor schemata Relaxion of a tension directed to a satisfactory gestalt Compensative homeostatic device From goal to movements Top-down: (from a pragmatic meaning to the interpretation of perceptual data): Bottom-up (from a collection of perceptual data to a pragmatic meaning): 1. kinaesthetic variations (provoked) -> 2. motor effects (executed) -> 3. idea of goal (extracted) Ideo-motor Adaptation Learning Imitation Intentional arc Mechanics of equilibrium 1. idea of goal (evoked) -> 2. motor effects (executed) -> 3. kinaesthetic variations (expected) The world must adapt to the action Knowledge of motor ideas anticipates the kinaesthetic feed-back of the action Predictive: finds a likely action for a known goal by pretending that the observer has the same goal ("What would I do if I had the same goal?") Forward model (predictor): receives an efferent copy of the motor command and generates the expected sensory outcome for it Experience teaches how behaviour can be adapted to intentions Emulative learning: discovering a desirable achievable goal state generates the movements that lead to the goal Observation of goal-oriented action triggers the execution of the same holistic complex motor schema Breaking of a satisfactory gestalt and creation (explosion) of tension Competition of different motor instances Remapping far and near space by means of sensorimotor and ideo-motor processes Experiments on patients with neglect in near or far space provide a very promising case for putting this scheme at work; these experiments, indeed, look capable of confirming that the experience of goal-oriented actions can be modulated both through a sensorimotor process and through an ideo45 46 Gallese & Goldman (1998). Wolpert & Ghahramani (2000). 20 motor one, depending on the pragmatical background of the execution and on the subjective approach assumed toward the tasks. This can be useful in order to show that the sensorimotor process is not the only form of motor intentionality, that the ideo-motor process is not necessarily a form of cognitive intentionality, and that the two processes are symmetrical counterparts of the same motor intentional experience of goal oriented action. A series of experiments carried out at first by Anna Berti and Francesca Frassinetti (2000), and later developed by Neppi-Mòdona et al. (2007) have shown that the mapping of near/far space doesn’t depend only on metric parameters, but can be determined by the pragmatic approach assumed for reaching the goal of the task. The very same distinction between a near space (peripersonal, i.e. it can be reached by hands) and far space (extrapersonal, i.e. it can only be pointed at) is not mapped in the brains as objective topological variations in a metric space, but it is mapped according to the kind of pragmatical and goal-oriented approach that the subject uses toward its experiential space. Different tools (a very long stick or a laser pen) used in tasks of linear bisection allow the subjects with neglect to transform the near-space-tasks into the far-space-tasks, and viceversa: in facts, a task performed with a very long stick is phenomenologically mapped as “peripersonal”, even if it is set beyond the extension of the patient’s arm, and a task performed with a laser pen is mapped as “extrapersonal” even if it is carried out in the objectively hand-reachable space of the patient. This way, patients with peripersonal neglect could accomplish a goal-oriented action in near space remapping the space by means of a “far” approach, and patients with extrapersonal neglect could accomplish a goal-oriented action in far space remapping the space by means of a “near” approach. The choice of the tool allows the familiar cognitive space of the neglect patient to be remapped, by transforming the space that is commonly just “observable” in “reachable”, and viceversa, in accordance with the pragmatical approach enabled by the used tool. This result shows the existence of a strong association between the near/far constitution of experiential space and the reachable/pointable nature of space in goal-oriented actions, but it still doesn’t discriminate between the different casual processes that can possibly underlie this association. These empirical conclusions are conceptually developed in Neppi-Mòdona et al. (2007), where an experiment about near/far spatial remapping in neglect patients is documented. The experimenters aimed to investigate “whether the representation of ‘near’ and ‘far’ space depends on the sensory feedback during the execution of the action or whether it is independent on sensory feedback, and more related to the action programmed as a consequence of the kind of tool used.” This question is highly relevant for the present enquiry because exploits the same distinction that is noticeable thanks to the symmetrical relationship between the sensorimotor approach (the goal is a consequence of kinesthetic variations, so that the latter anticipates the formers) and the ideo-motor approach47 (the kinesthetic variation is a consequence of the motor goal of the action, so that the former is an expected outcome of the latter) in goal-oriented intentional actions. For answering the proposed question, the Italian research group has asked patients to perform again the linear bisection task with long stick in either normal conditions and in conditions of missing perceptual stimuli. The experiment has then been repeated with full visual and tactile feed-back, with visual feedback but without tactile feedback (by mounting a very soft piece of tissue on the tip of the stick, preventing any feeling of tactile contact with the object), with tactile feedback but without visual feedback (by hiding the final part of the stick with a panel), without both visual and tactile feedbacks. The results obtained in these conditions show that “sensory feedbacks are not necessary for remapping to occur”, since the visual discontinuity or the tactile discontinuity are not capable, in themselves, to prevent the transformation of far into near. The authors conclude that “at least in some cases, simply thinking to an action, depending on the intrinsic functional characteristics of the tool used, activates the space that is congruent with that action. In other words the remapping effects that we observe in our patients may depend on the 47 The notion of “ideo-motor action” is not used by the authors of this study but, as I’m going to show soon, the corresponding concept defined so far seems to fit the experimental setting and the theoretical expectations connected to the study. 21 consciousness of the action that the patient is executing with a specific tool and not simply on tool use per se. However, our results also show that when ‘thinking to an action’ does not a priori trigger a compatible space representation, then remapping can still be obtained during the execution of the action, and it is contingent upon both the spatial relation that the tool induces between the body and the target object and the kind of sensory feedback available to the subject.” This means that, according to the conceptualization I have proposed, the capability of thinking to an action triggers an a priori ideo-motor process for goal-oriented tasks, while the sensory feedback constitutes the precondition for contingently processing the same goal-oriented task during a sensorimotor process. These concepts bring to a further articulation of the general frame formerly defined by Sean Kelly (2002) within his account of Merleau-Ponty’s motor intentionality. Kelly’s phenomenological interpretation concerns the famous experiments of Milner and Goodale (1995), involving a patient with a peculiar visual deficit that prevented her to recognize even the simplest geometrical features of the objects, but that didn’t prevent her to perform complex practical tasks on the very same objects. Kelly has effectively stressed the existence of a dissociation between a cognitive intentionality (addressing a spatiality of position, measured in an objective geometry according to Merleau-Ponty) and a motor intentionality (addressing a spatiality of situation, governed by an embodied intelligence adherent to the pragmatical context). According to Kelly, this distinction seems also to suggest that, while “grasping is the canonical motor-intentional activity”, the task of “pointing” is essentially a task involving cognitive intentionality48. This dissociation is confirmed by the experiments performed by Neppi-Mòdona et al., and thanks to them we can also individuate a further dissociation, that is internal to motor intentionality: in facts, we must acknowledge that a spatiality of situation (like the one accessed by patients in Neppi-Mòdona’s experiment, while reaching their target with a stick) can be modulated in two ways, depending on the fact that the logical priority is given to the “thought” of the goal (over the kinematics) or instead to the perception of the kinematics (over the goals), in accordance with the contingent perceptual situation of the action. The alternate prominence of the sensorimotor process or of the ideo-motor process, according to Neppi-Mòdona’s experiment, varies among different patients and it is supposed that it varies in accordance with the lost of abstractive capabilities in motor tasks due to cognitive damages. The different results obtained in a condition of competing stimuli (visual without tactile, or tactile without visual) show that “different sensory feedbacks have different weights in activating near and far space representations”, since the sensorial expectations deriving from sight act before the sensorial expectation deriving from touch: the former ones are more connected to the preparation of the motor program (motor idea) one instant before the execution of the action, while the latter ones are connected to the feedback obtained during the action. The authors suggest then that “tool use can influence far and near space coding, either with an automatic activation of an action space (Colby, 1998) compatible with the intrinsic characteristic of the tool, or by an adjustment of space coding based on the sensory feedback available to the subject. This adjustment is possibly mediated by bimodal neurons that enlarge or contract their vRF on the basis of the sensory feedback they receive during action execution.” The authors underline that the sensory feed-back intervenes in modulating the space of action only if the action started without a clear idea of the motor goal, or if the motor program was lacking in the initialization of the movements; this suggests that often, or at least when the agent prepares 48 Kelly’s distinction between pointing, reaching and grasping is enriched by sophisticated phenomenological analyses that it is not possible to report or to discuss here. In would be very interesting to develop the comparison between Kelly’s analysis and the experimental results concerning near-far spatial remapping. In facts, it seems necessary to discuss the possibility that even the mere act of “thinking” to the purpose of the “pointing” action is still a motorintentional process; this would be probably true provided that the thought motivating the action is not a sort of mental representation, but an ideo-motor idea compelling the body to act purposefully according to a motor task. This would show that also the spatiality of position can be affected by the spatiality of situation, and that the former is derived from the latter. 22 simple goal-oriented intentional actions, the ideo-motor approach can have some priority on the sensorimotor approach, since a fully structured intentional action always starts from a motor idea preshaping the goal-directed movements. The authors suppose then that bimodal neurons could be responsible for the normal capability of approaching motor tasks with a sensorimotor approach or with an ideo-motor approach. But its seems reasonable that this hypothesis could involve also mirror neurons: in facts, their functioning is not only potentially bi-modal, but it is also concerned with the reversibility between executed and perceived actions or – even more relevant in this context – between intentional goal-oriented classes of organized motor programs and simple, contingently instantiated movements. Conclusive remarks: mirror neurons at the midpoint of motor intentionality After this discussion on the plausible complementarity between sensorimotor and ideo-motor processes in the general framework of embodied cognition and skilful coping, it is necessary to discuss if skilful coping enacted by mirror neurons amounts to an ideo-motor process or not. The most likely answer is “no”, because the ideo-motor process, considered as standing alone, misses the same point that has already been missed by the sensorimotor process. Also in this case, indeed, the problem is not that motor ideas could not present a dual criteria of intervention (perceptual and performative), because studies on imitation have clearly stated that motor ideas can very likely do it. But, once again, the modality of this matching process between motor effects (goals) and stimuli (expected feed-back) is not of the right kind, because it still keeps these two sides of motor intentionality separated: motor ideas, in themselves, are not motor schemata provided with intentional meaning, and then they don’t contain a fully embodied intentional meaning expressed in a motor format, like mirror functions would require. Motor ideas, according to James and to Prinz, are off-line contents of experience that can produce and eventually accompany the executed/recognized action; they express some experiential feature generally associated to the goaloriented action, because they anticipate the kinesthetic effects of the action, and moreover they immediately motivate the action through thought or imagery, but they don’t express how the action should be done from the point of view of the concrete pragmatical project instantiated by motricity. Let’s look at James example: the idea of the cold room and the idea of going out of bed carry different subjective contents that we can define as simulated off-line experiences; they are able to motivate and trigger intentional reactive motor actions, but none of them is actually the expression of a goal-oriented motor program. Both are intentional contents and both motivate the body to act, but they don’t consist in a motor description of the action: the thought behind the action is still different, from the cognitive point of view, from the motor competence necessary in order to act purposefully. In this sense, motor ideas don’t provide a fully embodied account of motor intentionality, but just a partly embodied experiential content situated behind the motor intentional process. That’s why ideo-motor theory can admit that mirror neurons are elicited by motor ideas, both in performative or in perceptual ways, but it still reduces mirror neuron vocabulary to a simple function of execution that is controlled somewhere else, by higher cognitive agencies situated in associative areas of posterior parietal cortex (i.e. in functions related to more abstract intellectual activities). This means that also ideo-motor theory, like sensorimotor theory, misses the main point of motor intentionality; both of them are unable to provide a fully embodied account of motor competences embedded with meaningful motor goals. Merleau-Ponty’s phenomenology suggests that mirror-neuron-based motor intentional activity detains a logical and phenomenological priority over the sensorimotor and over the ideo-motor processes, because its related motor goals belong to an originary embodied experience, and are not derived from higher or lower functions that would produce their description from thought or from perceptual cues. In this sense, the instantiation of motor goals, during every day actions, neither amounts to a bottom-up nor to a top-down process, because it is neither laying on the extraction of perceptual invariants (sensorimotor process), nor on the expression of previously simulated off-line 23 experiential contents (ideo-motor process). It is necessary to underline that the goal of the action anticipates and models the structure of the action itself (and for this reason the motor goal is not a perceptual schema): at the same time, we must remember that the goal of the action is not located somewhere else than in the constituent dynamic bodily elements of the action, and that it is fully embedded in their intrinsic systemic relations (and for this reason the motor goal is not a thought or an idea). Mirror neuron device is quasi-independent from perception and from thought, but it is not encapsulated from the sensorimotor and the ideo-motor processes, since it always keeps at least a minimal interaction with them. The access to motor goals involved in mirroring processes depend though (at least indirectly) on kinaesthesia and on ideas, but their elaboration is brought out almost autonomously by specifically dedicated dual functions which are instantiated by pre-motor cortex (both during execution and during recognition). It is plausible that motor goals, i.e. the embodied knowledge concerning “how-to-move-for”, influences (during imitation) and is influenced by (during learning) both the sensorimotor and the ideo-motor processes: that’s why it is possible that mirror neurons constitute the condition of contact/reversibility between them, and a base of shared competences that can be accessed in both processes. The centrality of mirror neuron position in fully embodied functions is revealed by some features that are similar to sensorimotor and to ideo-motor partially embodied processes: - like sensorimotor processes, and unlike ideo-motor processes, mirror neuron functions enable a continuous modulation of action in accordance with perception (this enables the acquisition of new skilful coping - by means of the creation of new motor definitions in mirror neuron vocabulary - and joint action); - like ideo-motor processes, and unlike sensorimotor processes, mirror neuron functions enable an immediate transformation of perceived schemata into action (this enables the imitation of already acquired motor schemata, according to the ideo-motor compatibility principle); - unlike both sensorimotor and ideo-motor processes, mirror neuron functions express directly into a motor format the expertise necessary for coping, without needing the goals to be previously mapped into sensorial or imaginative structures. In cognitive terms, this is the reason of the greater adaptivity and economicity of mirror functions; in facts, a direct mapping of goals into motor structures excludes the necessity of accessing other cognitive devices when some sort of coping must be smoothly and quickly executed/recognized; - like both processes, mirror neuron functions enable a direct association of perceptual contents and motor contents; but, while for the two processes the goal of the action and the kinematic of its execution remain two different things, the goal accessed by mirror neurons is fully embodied in its kinematic expression, because it is completely and directly mapped into the motor program expressing its intentional meaning. Recently, Rizzolatti and Sinigaglia (2008, p. 589) have underlined this concept in a very sharp way: mirror system, according to them, “directly maps sensory information on cortical motor neurons, providing the observer with an immediate representation of the motor acts being performed by others. There is no need for a higher-order association”, which is instead required by other processes. For the sensorimotor process the association goes from a series of contingent perceptual stimuli to the abstraction of a general idea of goal, while for the ideo-motor process the association follows the opposite direction: mirror functions represent the only instant in which the idea of the goal and its kinaesthetic expression fully coincide, becoming reversible. This helps to provide a richer definition of motor goals. In the sensorimotor and in the ideo-motor classical accounts, the intentional goal is positioned, respectively, at the end and at the beginning of the execution/perception of the action, and for this reason both of them reduce motor experience to a subordinated procedure of simple execution. But both these accounts, considered singularly, fail to understand motricity as intrinsically embedded with an intentional meaning (as it appears by means 24 of mirror neurons activation during purely perceptual tasks); on the other hand, it is true that each of them, considered within a wider embodied perspective, can enable the comprehension of one side of the motor intentional activity; but how to think motor intentionality as the very centre of the two processes? In order to understand the embodiment of motor goals into action, it is necessary to think that the sensorimotor process and the ideo-motor process are not alternatives, but inverted cognitive modes running through two opposite directions of the very same general circuit; and moreover it is necessary to think that motor intentionality originates from, and goes back to, the midpoint of this integrated system, considerable as the barycentre of their chiasmic relation. Mirror system could perhaps be interpreted as the crossing point between the two symmetrical and reciprocally reversible directions of motor intentionality, because it is involved in both sensorimotor and ideo-motor processes; this seems plausible since mirror neurons codify the intentional meaning of motor goals and the correlated possibilities of kinaesthetic variations by means of a commonly shared motor format. Moreover, they are involved in the processes concerning both the general abstraction of the goal from the intentional movements and the instantiation of the particular movements according to a motor intention: they mediate the elaboration processes that go either from particular contingent movements to abstract classes of actions (learning), or in the opposite direction (imitation). If this suggestion could be confirmed, the double implication (sensorimotor and ideo-motor) of mirror neurons would perhaps explain more easily why, in our simplest intentional motor activities, we are able to immediately translate bodily movements into motor goals (because – in recognition tasks - the access to mirror-neurons-based motor schemata is already directly instantiating the comprehension of the goal of the action, as stated by the sensorimotor principle), and – vice versa – we are able to immediately translate simulated experiences and motor imaginations into effective bodily movements (because – in performative tasks – the activation of mirror-neurons-based motor goals is already directly motivating the execution of the action, as stated by the ideo-motor principle). 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