Sensation, Perception

SENSATION, PERCEPTION, ATTENTION AND SIGNAL DETECTION THEORY Sensation and Perception Perception involves using prior knowledge to interpret the sensory stimuli detected by our senses. For example, to read this text, you must:  Register visual information from the page using your eyes (sensation). visual field recognition. enabling rapid Anatomy of the Eye Key structures include: involved in vision  Sclera/cornea - Outer protective layer with transparent cornea for light entry.  Iris - Pigmented, controls pupil size to regulate light levels.  Pupil - Variable aperture that controls light entering eye.  Recognize the shape of letters using knowledge of the alphabet (perception).  Lens - Transparent, focused by ciliary muscles, refracts light onto retina.  Understand words and sentences using language knowledge (perception).  Retina - Inner light-sensitive layer with rod and cone photoreceptors.  Fovea - Central retina area with high acuity/color vision due to dense cones.  Optic nerve - Exits eye and carries neural signals to brain.  Blind spot - Spot where optic nerve exits lacks photoreceptors.  Aqueous/vitreous Fluids providing nutrition. Perception relies on both bottom-up sensory input and top-down influences like expectations, context, and memories. Visual Object Recognition Object recognition involves identifying a meaningful pattern of sensory stimuli as distinct from the background. This requires:    Feature extraction - detecting basic stimulus attributes like edges, contours, color, movement. Pattern recognition - relating extracted features to stored object knowledge to identify and categorize the object. Parallel processing - features detected simultaneously across humors shape and Anatomy of the Ear Key auditory structures include:  Outer ear - Funnels sound waves down ear canal.  Middle ear Tympanic membrane and ossicles amplify and transmit vibrations.  Inner ear - Cochlea converts vibrations into neural signals sent to brain via auditory nerve.  Hair cells - Sensory receptors that detect specific sound frequencies.  Semi-circular canals - Detect head motion and orientation. Signal Detection Theory Signal detection theory examines decision-making in perception. Key principles:  Faint stimuli are detected against background noise.  Subject makes decision if signal is present based on available evidence.  Decision-making introduces cognitive influences beyond basic sensory processing.  Accuracy depends on signal strength relative to noise.  Provides framework for analyzing attention, memory and other cognitive processes. Attention and Perception Attention allows selectively processing relevant information. Perception theories include:  Bottom-up - Builds percepts from sensory features to whole objects.  Top-down - Uses knowledge and expectations to guide interpretation.  Template matching - Compares stimuli to stored templates.  Feature analysis - Recognizes stimuli by component features.  Recognition-by-components 3D object recognition using viewpoint-invariant geons.