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detect black, white or gray


detect well-lit light or daylight conditions

optic nerve

carries information to the brain. Its made up of axons

blind spot

the optic nerve leaves the eye and no receptor cells are present


the retina's area of focus, where the cones cluster


a process where we detect physical energy from the environment and encode it as neural signals


when we select, organize and interpret the sensations

bottom-up processing

using the sensory receptors to detect the lines, angles, and colors that form an image

top-down processing

to process information by constructing perceptions drawing on our experience and expectations


the study of the relationship between physical energy and our psychological experience

absolute thresholds

the minimum stimulation necessary to detect a particular light, sound, pressure, taste, or ordor 50% of the time


below absolute threshold for conscious awareness


the activation of certain associations, predisposing one's perception, memory or response

difference threshold

the minimum difference a person can detect between any two stimuli half the time

Weber's Law

for something to be perceived as different, as two stimuli must differ by a constant proportion-not a constant amount

sensory adaptation

our diminishing sensitivity to an unchanging stimulus


the distance from one peak to the next


the color we experience determined by the wavelengths


the amount of energy in light waves


the process in which the lens changes shape to focus near or far objects on the retina

feature detectors

nerve cells that enter the brain responding to specific features of the stimulus such as shape, movement, or angle located in the occiptal lobe


the processing of many aspects simultaneously in the brain

Young-helmholtz trichromatic (three color) theory

the retina has three types of color receptors, each especially sensitive to one of the three colors; red, green, and blue, and when these cones are combinationally stimulated, we see other colors

Opponent-Process Theory

the opposing retinal processes enable color vision. (red-green; yellow-blue; white-black)


an organized whole


the organization of the visual field into objects (figures) that stand out from their surroundings (ground)


organizing stimuli into coherent groups


group nearby figures together


we group similar figures together


to perceive smooth, continuous patterns rather than discontinuous ones


perceiving two dots and a line as a single unit


fill in gaps to create a complete, whole object

Depth Perception

estimating the distance between us and an object which we see in 3 dimensions

Visual Cliff

a laboratory device used to test depth perception in infants and young animals

Binocular Cues

depth cues that depend on the use of two eyes

Retinal Disparity

difference computed with the use of the eyes between two things

Monocular Cues

depth cues that are available to either eye

Relative Height

perceive objects higher in our field of vision as farther away

Relative Motion

as we move, objects that are stable appear to move

Relative Size

if we assume objects are similar in size, the one that casts the smaller retinal image is farther away


if one object partially blocks our view of another we perceive it as closer.

Light and Shadow

nearby objects reflect more light to our eyes

Perceptual Constancy

perceiving objects as unchanging even as illumination and retinal images change

color constancy

perceiving familiar objects as having constant color, even if changing illumination alters the wavelengths reflected by the object

perceptual adaptation

invision to adjust to an artificially displaced or even inverted visual field

perceptual set

mental predisposition to perceive one thing and not another

Extrasensory Perception

the controversial claim that perception can occur apart from sensory input


mind-to-mind communication


perceiving remote events


perceiving future events


mind over matter {ex: levitating a table}


the study of ESP and psychokinesis


our hearing


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


a tone's experienced highness or lowness {depends on frequency}

middle ear

the chamber between the ear drum and the cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window


a coiled, bony fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

inner ear

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

gate-control theory

theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain; the spinal cord nerve fibers conduct most of the pain signals

sensory interaction

the principle that one sense may influence another {the smell of food influences its taste}


the system for sensing the position and movement of individual body parts

vestibular sense

the sense of body movement and position, including the sense of balance

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