AP Psychology: Unit 4

Sensation and Perception

sensation

the experience of sensory stimulation

perception

the process of creating meaningful patterns from raw sensory information

bottom-up processing

analysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind

top-down processing

Information processing is guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations

selective attention

focusing on one particular stimulus or task while ignoring all other competing stimuli in the environment

cocktail party effect

the ability to focus your attention on a particular stimulus while filtering out all other sounds

change blindness

failure to notice changes in the environment

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

transduction

the process of converting sensory stimuli into neural signals that can be interpreted by the brain (conversion of one form of energy into another)

psychophysics

the study of relationships between the physical characteristics of stimuli and our psychological experience of them

absolute threshold

smallest detectable level of a stimulus, detection must be 50% of the time

signal detection theory

Predicts how and when we detect the presence of a faint stimulus (signal) amid background noise (other stimulation). Assumes there is no absolute threshold.

subliminal

when energy of the stimulus is below one’s absolute threshold for conscious awareness

priming

exposure to one stimulus influences the response to a subsequent stimulus without conscious guidance or intention

difference threshold (just noticeable difference)

the smallest detectable change between two stimuli (50% of the time)

Weber’s law

two stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

a bias or readiness to perceive certain aspects of available sensory data and to ignore others

transduction

the process of converting sensory stimuli into neural signals that can be interpreted by the brain

wavelength

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

hue

the dimension of color that is determined by the wavelength of light

intensity

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave’s amplitude

pupil

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

cornea

the transparent, dome-shaped outer layer at the front of the eye that protects the eye and helps with vision by focusing light rays onto the retina

iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

accommodation

the process by which the eye’s lens changes shape to focus near or far objects on the retina

acuity

the sharpness and clarity of vision, specifically the ability to see fine details

nearsightedness

a vision condition where close objects are seen clearly, but distant objects appear blurry

farsightedness

a vision condition where distant objects are seen more clearly than near objects

photoreceptors

specialized neurons in the retina that detect light and convert it into electrical signals the brain can process

rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond

cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. They detect fine detail and give rise to color sensations.

bipolar cells

cells in the visual system that connect the photoreceptors (rods and cones) to the ganglion cells

ganglion cells

specialized neurons in the retina that receive information from bipolar cells and transmit it to the brain via the optic nerve

optic nerve

the nerve that carries neural impulses from the eye to the brain

blind spot

the point at which the optic nerve leaves the eye, no receptor cells are located there

fovea

the central focal point in the retina, around which the eye’s cones cluster

feature detectors

nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

David Hubel & Torsten Wiesel

demonstrated that the visual cortex contains specialized neurons called feature detectors that respond to specific visual stimuli like edges, lines, and angles

parallel processing

the processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions

Young-Helmholtz trichromatic (three-color) theory

the theory that the retina contains three different color receptors - one most sensitive to red, one to green, one to blue - which, when stimulated in combination, can produce the perception any color

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision

color constancy

our brains perceive an object's color as consistent despite changes in illumination, or the type of light reflecting off it

gestalt

our tendency to integrate pieces of information into meaningful wholes

figure-ground

the organization of the visual field into objects that stand out from their surroundings

stroop task

measures cognitive interference, attention, and executive function by requiring participants to name the ink color of a word while ignoring the word itself

grouping

the perceptual tendency to organize stimuli into coherent groups

proximity

we group nearby figures together

similarity

we perceive things that are alike in some way (like color, shape, or size) as being related or belonging to a group

continuity

we perceive smooth, continuous patterns rather than discontinuous ones

connectedness

we group objects together that are joined by lines or borders

closure

we fill in gaps to create a complete, whole object

depth perception

the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

visual cliff

a laboratory device for testing depth perception in infants and young animals

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

retinal disparity

a binocular cue for perceiving depth: by comparing images from the retinas in the two eyes, the brain computes difference between the two images, the closer the object

convergence

a binocular cue for depth perception, describing the inward rotation of both eyes to focus on a close object

monocular cues

depth cues, such as interposition and linear perspective, available to either eye alone

relative size

if we assume two objects are similar in size, most people perceive the one that cast the smaller retinal image as farther away

interposition

if one object partially blocks our view of another, we perceived it as closer

relative clarity

a monocular depth cue where sharper, clearer objects are perceived as closer, while hazy or blurry objects are perceived as farther away

texture gradient

a monocular depth cue where the brain perceives distance because textures appear more detailed and coarse up close, becoming finer, smoother, and more compressed as they move further away

relative height

we perceived objects higher in our field of vision as farther away

relative motion/motion parallax

as we move, objects that are actually stable may appear to move

linear perspective

parallel lines appear to meet in the distance

light and shadow

shading produces a sense of depth consistent with our assumption that light comes from above

apparent motion

the illusion of movement created by flashing two or more stimuli in different locations in quick succession

stroboscopic movement

the brain perceives continuous movement in a rapid series of slightly varying images

phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession

perceptual constancy

perceiving objects as unchanging (having consistent shapes, size, brightness, and color) even as illumination and retinal images change

perceptual adaptation

in vision, the ability to adjust to an artificially displaced or even inverted visual field

audition

the sense or act of hearing

frequency

the number of complete wavelengths that pass a point in a given time

decibels

a unit used to measure the intensity or loudness of a sound

pitch

a tone’s experienced highness or lowness; depends on the frequency

middle ear

the chamber between the eardrum and cochlea containing three tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window

cochlea

a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the fluid trigger nerve impulses; transduction occurs here

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

basilar membrane

a thin, flexible strip of tissue inside the inner ear's cochlea that vibrates in response to different sound frequencies

place theory

we hear different pitches because different sound waves trigger activity at different spots along the cochlea’s basilar membrane (hard to determine location on the basilar membrane where low pitch stimulates)

frequency theory

the brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve

sound localization

the perceptual process of determining the location of a sound's origin

conduction hearing loss

hearing loss caused by damage to the mechanical system that conducts sounds waves to the cochlea

sensorineural hearing loss

hearing loss caused by damage to the cochlea’s hair cell receptors or to the auditory nerve; also called nerve deafness

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

gate-control theory

the theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain

cutaneous receptors

specialized sensory receptors in the skin that detect and respond to a variety of stimuli, including pressure, warmth, cold, and pain

sensory interaction

the principle that one sense may influence another

olfaction

the sense of smell

umami

one of the five basic tastes, described as a savory or meaty flavor

kinesthesis

our sense of body position and movement of the body

vestibular sense

helps regulate our balance when we move and keeps us upright when we sit or stand

synesthesia

experience two or more senses at once

prosopagnosia

a neurological condition where a person is unable to recognize familiar faces

auditory canal

channels sound vibrations into the middle and inner ear

eardrum

transmits and amplifies sound waves, protects the middle ear from contaminants

oval window

vibrates when it receives sound waves and causes the fluid inside the cochlea to move

hair cells

perform transduction in the ear