Psychology - Perception and Sensation

Perception and Sensation Sensation: the stimulus-detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain Perception: making “sense” of what our senses tell us– the active process of organizing this stimulus input and giving it meaning. (how you interpret it) Senses: Vision Audition (hearing) Gustation (taste) Olfaction (smell) Touch Pressure, pain, temperature Absolute Threshold: How intense does a stimulus need to be before we can detect its presence? This is the “absolute threshold” – the lowest intensity at which a stimulus can be detected 50% of the time. The lower the absolute threshold, the greater the sensitivity Signal Detection Theory: Your sensitivity to various stimuli fluctuates Decision Criteria: A standard of how certain a person has to be that stimulus is preset before they will say that they detect it. The Difference Threshold The smallest difference between two stimuli that people can perceive 50% of the time. Sometimes called the “just noticeable differences) o How much can we change in the packaging without people noticing. Weber’s Law: Difference Threshold o The JND directly proportional to magnitude of the stimulus with which the o The more intense the stimulus is the more change that you need to notice the difference”  Examples: when you carry 50g and then its 51g you can tell the difference and if it’s a 500g it takes 510 g to tell the difference. Habituation Habituation = diminishing sensitivity to an unchanging stimulus o You put on a shirt with an itchy tag and wear it for a long time you won’t notice it after a while. o Also known as sensory adaptation Vision In the Retina: o Rods: function best in dim light and are primarily black and white brightness receptors o Cones: color receptors function best in bright illuminations Past Theories of Color Vision Trichromatic (three color theory)” o Cones are sensitive to either blue, green, or red wavelengths. The visual system combines these signals to recreate the color you see Opponent-Processing Theory: o There are three types of cones, but each one responds to two different wavelengths (blue/yellow, red/green and black/white)  When you see a color with the opposite color and then you see a blank screen you’ll see the actually colors Dual Process in Color Transduction Theory o Combines the two prior theories  Cones contain one of three different photopigments that are most sensitive to either red, blue, or green (trichromatic)  Opponent processes do happen… but not in the cones. They occur with the ganglion cells in the retina and in the neurons in the visual relay stations and in the visual cortex. Synesthesia Synesthesia is a neurological condition in which two or more senses are coupled, with one sense input creating an involuntary connection to another. o For example, someone may “see” sounds, “taste” colors, or “feel” flavors. “Grapheme–color synesthesia” is one of the most popular forms of synesthesia in which someone perceives letters and numbers as having a specific color. o This may be caused by cross-activation since the neural regions for processing letters and numbers lies adjacent to those for color. KNOW THIS Audition Sound Waves: o Frequency (related to pitch) (horizontal size) o Amplitude (related to volume) (vertical size) The ear: o THREE BONES in ear and the smallest  Auditory canal → Eardrum → Middle ear (hammer, anvil, and stirrup bones) → inner ear (cochlea) o Eustachian tube connects the middle ear to the throat Types of hearing loss Sensorineural (no hearing aid) o Aging o Noise damage o Drug side effects o Auditory tumors o Blast/explosion Conductive (hearing aid) o Fluid o Foreign objects o Allergies o Ruptured eardrum o Impacted earwax Mixed o Genetic Disorders o Infections o Head Trauma Taste Sweet Sour Salty Bitter Umami (savory) Sweet vs bitter evolutionary advantage Born with taste Olfaction Humans have about 40 million olfactory receptors (dogs have ~100 million) Pheromones: A chemical substance produced and released into the environment by an animal, affecting the behavior or physiology others of its species. Touch Humans have at least 4 tactile sensations (pressure/touch, pain, warmth, and cold) The skin is the largest organ in the human body Primary receptors for pain and temperature are free nerve endings The brain can locate sensations through the somatosensory cortex This is the Homunculus for sensory PERCEPTION DOWN Perception Bottom-up processing can be defined as sensory analysis that begins at the entry-level—with what our senses can detect. In top-down processing, perceptions begin with the most general and move toward the more specific. These perceptions are heavily influenced by our expectations and prior knowledge. Selective Attention What we pay attention to at a time o EX: a group of black and white shirts are tossing a ball notice how many times they pass to white but in the middle of the video there is a gorilla but don’t see it Studies show we can’t multitask at the same time rather we look at one thing then at another things Motivation can change the way we react to stimulus such as if you are expecting a call and you go away from your phone you’ll here like a phantom buzz if you’re a mom and you are here your baby in the middle of the night, you’ll wake up immediately, but you won’t wake up if you here load noises like a truck Muller-Lyre illusion ----------------------- what you see changed depending on context Gestalt Even your personality can change your personality such as if you were a thrill seeker your more likely to pick super duper sour things The whole is greater than the sum of the parts (the whole song is better than individual lyric) o Figure Ground Relationship: is when there are two pictures of things in one image but if you look at one thing it looks like a different picture o Proximity: Things that are close to one another tend to be grouped together. o Similarity: if its together it looks better than different colors o Continuity and closure: you look at an x it looks like two lined rather than than four Review Questions: 1.Absolute Threshold refers to the minimum amount of stimulus energy required to be detected 50% of the time. 2.Decreased sensitivity to an unchanging stimulus is known as Habituation or sensory adaptation. 3.Cones operate best under bright light conditions. 4.Cones and rods are located in the in the eye in the retina. 5.If you were to stare at a green dot for a relatively long period of time and then shift your gaze to a blank white screen, you would see a Green negative afterimage. 6.There are three ossicles (small bones) in the middle ear. 7.According to the principle of proximity gestalt principal objects that occur close to one another tend to be grouped together. 8.The main point of focus in a visual display is known as the figure ground relationship