Psych Ch 6

sensation

sensation

process of sensory receptors and the nervous system receive and represent stimulus energies from environment (ex. pressure, texture, temperature receptors giving info to brain)

perception

process of organizing and interpreting sensory info, allows recognition of meaningful objects/events, what your brain does with sensory information

bottom-up processing

analysis begins with sensory receptors, works up to brain integration of sensory info

top-down processing

info processing guided by higher level mental processes, constructing perceptions drawing on experience and expectations, “magenta vs pink”

transduction

conversion of stimulus energies (sights, sounds, smells) into neural impulses brain can interpret, sensation becomes perception

psychophysics

study of relationships between physical characteristics of stimuli (intensity) and psychological experience of them

absolute thresholds

minimum stimulus energy needed to detect a particular stimulus 50% of the time, found by Gustav Fechler (German scientist and philosopher)

signal detection theory

a theory predicting how and when we detect presence of faint stimulus amid background stimulation, assumes there is no single absolute threshold and detection depends on persons experience, expectation, motivation, and alertness. Gives reason as to why people respond differently to the same stimuli/why same persons reactions vary as circumstance change

subliminal

below ones absolute threshold for conscious awareness, stimuli cannot detect 50% of the time, don’t affect physically

priming

activation unconsciously of certain associations, thus predisposing ones perception, memory, response. unnoticed image and word influence answer

masking stimulus

interrupts the brains processing before conscious perception

difference threshold

minimum difference between 2 stimuli required for detection 50% of the time, experience as just noticeable difference (jnd), increases with size of stimulus

Weber’s Law

to be perceived as different, 2 stimuli must differ by constant minimum percentage rather than constant amount, proportion depends on stimulus

sensory adaption

diminished sensitivity as consequence of constant stimulation, allows for focus on informative sensitivity rather than the background (ex. odors disappearing as you get used to it)

perceptual set

unconscious mental predisposition to perceive one thing and not another, preexisting schemas influence how we apply top-down processing to interpret unfamiliar sensations (ex. optical illusions)

context effects

given stimulus trigger radically different perceptions from immediate context

wavelength

distance from peak of one light/sound wave to peak of the next

hue

dimension of color determined by wavelength (ex. blue, green, etc)

intensity

amount of energy in light/sound wave, influences brightness/loudness, determined by amplitude (height of wavelength), measured in lumen, not interpreted

pupil

adjustable opening in the center of the eye through which light enters

cornea

where light enters the eye, bends light to provide focus

iris

ring of muscle tissue form colored potion of eye around pupil, controls size of pupil opening, dilates/constricts in response to light intensity/emotion

lens

transparent structure behind pupil, changes shape to help focus image on retina

retina

light-sensitive inner surface of eye, contains receptor rods and cones and layers of neurons beginning processing of visual info, image projected upside-down on retina

accommodation

lens changes curvature and thickness to focus near/far objects on retina

fovea

point of central focus, eye cones cluster

rods

retinal receptors that detect black, white, gray, creates general image of shapes, necessary for peripheral and twilight vision when cones don’ t respond, share bipolar cells to send info to brain

cones

retinal receptor cells concentrated near center of retina, function in daylight/well-lit conditions, detect color and fine details and color sensations, have their own bipolar cell to transmit info to brain

optic nerve

nerve that carries neural impulses from eye to brain, made of ganglion cell axons that twine together like rope

pathway from light to thalamus

light triggers chemical changes, that spark neural signals, that activate bipolar cells, that activate ganglion cells (optic nerve), info distributed by thalamus

blind spot

point where optic nerve leaves eye, no receptor cells located there

Young-Helmholz Trichromatic Theory

retina contains three diff color receptors, one sensitive to red, green, or blue. when stimulated in combination, perception of colors is produced

color-deficient vision

lack functioning red/green cones (ex. red-green color blind)

opponent-process theory

opposing retinal processes that enable color vision (red/green, yellow/blue, white/black), some cells stimulated by green, inhibited by red, red and green messages cannot both travel at once, only one is transmitted, retina red, green, blue cones respond in varying degrees to different color stimuli, cones responses processed by opponent-process cells

feature detectors

nerve cells in brain that respond to specific features of stimulus (ex. shape, angle, movement), some neurons fire actively when cats shown lines at an angle, receive info from individual ganglion cells in retina, pass info to other cortical area teams of super cell clusters to respond to more complex patterns

parallel processing

processing of many aspects of problem simultaneously, brain natural mode of info processing for many functions, divides into sub dimensions (ex. motion, form, depth, color)

gestalt

organized whole, emphasized our tendency to integrate pieces of info into meaningful whole images, “whole may exceed sum of its parts”

figure-ground

organization of visual field into objects (figures) that stand out from surroundings (ground), continually reverses, organize into meaningful form, process, basic features of scene instantly and automatically (ex. color, movement, light-dark contrast)

grouping

perceptual tendency to organize stimuli into coherent groups, follow certain rules show how perceived whole differs from sum of its parts

proximity

group nearby figures together (ex. see 3 sets of 2 lines rather than 6 separate lines)

continuity

perceive smooth continuous patterns rather than discontinuous ones (ex. view as wavy and straight line rather than as semicircles)

closure

fill in gaps to create a complete, whole object (ex. assume circles on left blocked by illusory triangle, right circles brain stops constructing triangle

depth perception

ability to see objects in 3 dimensions although the images that strike retina are two dimensional, allows us to judge distance, estimate objects distance from us

visual cliff

lab device for testing depth perception in infants and young animals

binocular cues

depth cues that depend on use of two eyes, 2 eyes better than 1 (ex. retinal disparity)

retinal disparity

binocular cue for perceiving depth, compare images from retinas of both eyes, brain computes distance, the greater the distance between two objects, the closer the object is

monocular cues

depth cues available to either eye alone, (ex. interposition and linear perspective)

stroboscopic movement

brain perceives rapid series of slightly varying images as continuous movement (ex. animation)

phi phenomenon

illusion of movement created when two or more adjacent lights blink on and off in quick succession (ex. sign of moving arrow)

perceptual constancy

perceiving objects as unchanging even as illumination and retinal images change, can identify people regardless of angle, distance, illumination

color constancy

perceiving familiar objects as having constant color, even if changing illumination alters the wave lengths reflected by the objects, color depends on context

brightness constancy (lightness constancy)

perceiving object as having constant brightness even while illumination varies, depends on context

relative luminance

amount of light an object reflects relative to its surroundings, white paper reflects 90% of light, black paper reflects 10% of light, black paper viewed in sunlight still looks black

shape constancy

perceive form of familiar objects as constant even while retina receives changing images of them, visual cortex neurons rapidly learn to associate different views of an object

perceptual adaptation

ability to adjust to artificially displaced/inverted visual field, adapt to distorting glasses

audition

sense/act of hearing, helps adapt and survive, provide info and enable relationships

frequency

number of complete wavelengths that pass a point in a given time (per sec), length of wavelength

pitch

tones experienced highness/lowness, depends on frequency, short wavelength has high frequency and pitch, long wavelength has low frequency and pitch

auditory canal

visible outer ear channels waves through

eardrum

tight membrane causes vibration

middle ear

chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup), concentrate vibrations of eardrum on cochlea oval window

cochlea

coiled, bony, fluid-filled tube in inner ear, sound waves traveling through cochlear fluid trigger nerve impulses, snail shaped

inner ear

innermost part of ear, contains cochlea, semicircular canals, vestibular sacs

oval window

cochleas membrane covering entrance to cochlea, vibrations enter through here

vibration in inner ear

incoming vibrations causes vibration, jostling fluid filling tube, causes ripples in basilar membrane bending hair cells lining surface

auditory nerve

axons of adjacent nerve cells converge, sends neural messages through thalamus to auditory cortex

sensorineural hearing loss (nerve deafness)

most common form of hearing loss, caused by damage to cochlea receptor cells/auditory nerves, biological changes linked to heredity, aging, prolonged exposure to ear-splitting noise

conduction hearing loss

less common form of hearing loss caused by damage to mechanical system that conducts sound waves to cochlea

cochlear implant

device for converting sound into electrical signals and stimulating auditory nerve through electrode threaded into cochlea

place theory

theory link pitch we hear with the place where cochleas membrane is stimulated, by Hermann von Helmholz, brain recognizes specific place on membrane and generates neural signal, explains how we hear high-pitched sounds not low pitch, low pitch no neatly localized on basilar membrane

frequency theory (temporal theory)

rate of nerve impulses traveling up auditory nerve matches frequency of tone, enable sense pitch, frequency 100 waves per sec, 100 pulses per sec travel up auditory nerve, individual neuron cannot fire faster than 1000 times per sec

volley principle

neural cells alter rate of firing, achieves combined frequency of 1000 waves per sec, proves frequency theory possible

stereophonic hearing

three dimensional hearing (ex. car honk to right, right ear hears a more intense sound and sooner than left)

nocireceptors

sensory receptors in our skin, muscles, organs that detect hurtful temperatures, pressure, or chemicals, detect pain in response to potentially harmful stimuli

gate control theory

spinal cord contains neurological “gate” that blocks pain signals or allows them to pass on to brain, gate opened by activity of pain signals traveling up small nerve fibers, closed by activity in large fivers or by info from brain

umami

savory meaty taste, flavor enhancer of monosodium glutamate (MSG), indicates protein to grow/repair tissue

sweet

indicates energy source

salty

indicates sodium essential to physiological processes

sour

indicates potentially toxic acid

bitter

indicates potential poison

kinesthesia

system sensing position and movement of individual body parts

vestibular sense

sense of body movement and position including balance, biological gyroscopes two structures in inner ear

vestibular sacs

contained fluid moves when head rotates/tilts, connect semicircular canals with cochlea, stimulate hair like receptors and send messages to cerebellum at the back to your brain, sense body position/balance, cause dizziness

sensory interaction

principle that one sense may influence another, smell of food influence taste

McGurk effect

when eyes and ears disagree, seeing a speaker say one syllable but hear another syllable, perceive different syllable (ex. see “ga”, hear “ba”, perceive “da”)

embodied cognition

influence of bodily sensation, gesture, other states on cognitive preferences and judgments, brain blends input from multiple channels