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The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

sense receptors

Specialized cells that convert physical energy in the environment or body to electrical energy that can be transmitted as nerve impulses to the brain.

sense organs

Organs that receive stimuli.

bottom up processing

Analysis that begins with the sensory receptors and works up to the brain's integration of sensory information.


The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

top-down processing

Assessing sensory information based on previous experience or expectations.


Conversion of physical energy into neural information. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.

doctrine of specific nerve energies

The principle that different sensory modalities exist because signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain.


The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

absolute threshold

The minimum stimulation needed to detect a particular stimulus 50 percent of the time.

signal detection theory

A theory predicting how and when we detect the presence of a faint stimulus ("signal") amid background stimulation ("noise"). The four potential outcomes are hit, miss, false alarm and correct rejection.

just noticeable difference

The smallest difference that can be detected between two physical stimuli 50% of the time.

Weber's Law

Principle that the just noticeable difference of a stimulus is a constant proportion despite variations.

sensory adaptation

Diminished sensitivity as a consequence of constant stimulation.

Sensory deprivation

The absence of normal levels of sensory stimulation.

sensory overload

Experiencing multiple stimuli at once. An individual cannot properly attend to all stimuli at once.

selective attention

The focusing of conscious awareness on a particular stimulus, as in the cocktail party effect.


Intensity of reflected light that reaches our eyes.


Chromatic purity: freedom from dilution with white and hence vividness of hue.


Transparent anterior portion of the outer covering of the eye.


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


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


Muscular diaphragm that controls the size of the pupil.


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


The light-sensitive membrane covering the back wall of the eyeball.


The central focal point in the retina, which is the area in the retina of highest visual acuity and holds only cones.


Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.


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

dark adaptation

The process by which visual receptors become as sharp as they can in darkness. both rods and cones adjust but ultimately rods are more effective in darkness.

bipolar cells

Eye neurons that receive information from the retinal cells and distribute information to the ganglion cells.

ganglion cells

The specialized cells which lie behind the bipolar cells whose axons form the optic nerve which takes the information to the brain.

optic nerve

Nerve responsible for carrying impulses for the sense of sight from the retina to the brain.

blind spot

The point where the optic nerve enters the retina.

feature detectors

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


Sharpness of vision.


A condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina.


A condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina.

parallel processing

The processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision.

trichromatic theory

Visual theory, stated by Young and Helmholtz that all colors can be made by mixing the three basic colors: red, green, and blue; a.k.a the Young-Helmholtz theory.

opponent process

The representation of colours by the rate of firing of two types of neurons; red/green and yellow/blue.

negative after image

The image seen after a portion of the retina is exposed to an intense visual stimulus.

color blindness

Inability to perceive certain colors, such as red and green.


The ability to hear.


The human perception of how much energy a sound wave carries.


The property of sound that varies with variation in the frequency of vibration.


(music) The distinctive property of a complex sound (a voice or noise or musical sound).


Tightly stretched membrane located at the end of the ear canal that vibrates when struck by sound waves.


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

basilar membrane

The cellular membrane in which the hair cells are embedded. It moves in respose to pressure waves in the cochlea, initiating a chain of events that results in a nerve impulse traveling to the brain.

auditory nerve

A composite sensory nerve supplying the hair cells of the vestibular organ and the hair cells of the cochlea.

place theory

In hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated.

frequency theory

In hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

conduction deafness

Hearing loss due to problems with the bones of the middle ear.

nerve deafness

Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerve.


Sense of taste.

taste buds

Sense receptors in the tongue that respond to sweet, salty, sour, bitter, umami.

sensory interaction

The principle that one sense may influence another, as when the smell of food influences taste.


The sense of smell.


Airborne hormones released by one individual and taken in by another, usually of the same species, and impacts behavior.

gate-control theory

The idea that there is a "valve" in the spinal cord which when open allows pain messages to get to the brain and when closed prohibits these messages from reaching the brain.


Sense of one's physical position body parts to one another and to the ground.

vestibular sense

A sensory system located in structures of the inner ear that registers the orientation of the head.

semicircular canals

The structures in the innerear that are responsible for your sense of balance.


An organized whole - psychologists emphasized our tendency to integrate pieces of info into meaningful wholes.


A Gestalt principle of organization holding that (other things being equal) objects or events that are near to one another (in space or time) are perceived as belonging together as a unit.


A Gestalt principle of organization holding that there is an innate tendency to perceive incomplete objects as complete and to close or fill gaps and to perceive asymmetric stimuli as symmetric.


Gestalt law; sensations that appear to create a continuous form are perceived as belonging together (a whole).


Gestalt law; elements that are connected by other elements tend to grouped together.

binocular cues

Depth cues, such as retinal disparity and convergence, that depend on the use of two eyes.

monocular cues

Distance cues, such as linear perspective and overlap, available to either eye alone.

retinal disparity

A binocular cue for perceiving depth; by comparing images from the two eyeballs, the brain computes distance - the greater the disparity (difference) between the two images, the close the object.


Monocular visual cue in which two objects are in the same line of vision and one patially conceals the other, indicating that the first object concealed is further away.

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance.

relative size

A depth cue whereby larger objects are perceived as closer than smaller ones.

texture gradient

A monocular cue for perceiving depth; hazy objects are farther away than sharp, clear objects.

relative height

A monocular cue for perceiving depth; objects higher in our field of vision are perceived as farther away.

relative motion

The perception of an observer that, as the observer moves forward, the objects that appear to him/her to move backwards faster are closer than apparently slower-moving objects; a monocular cue.

relative size

Even though different images are being considered the same even though size on retina was changed.


Apparent communication from one mind to another without using sensory perceptions, the ability to read minds.


Apparent power to perceive things that are not present to the senses.


Knowledge of an event before it occurs.


The study of paranormal phenomena, including ESP and psychokinesis.


The ability to move objects with one's mind.

perceptual sets

Demonstrates our readiness to percieve in a particular manner; Based on experience and expectation.


The ability of the lens to bend in order to send incoming visual information onto the retina.


A visual image that persists after a stimulus is removed.

auditory canal

Channel that leads from the pinna to the eardrum.

brightness constancy

The tendency to perceive the apparent brightness of an object as the same even when the light conditions change.

volley principle

The theory holding that groups of auditory nerve fibers fire neural impulses in rapid succession, creating volleys of impulses.


A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object. The greater the inward strain, the closer the object.


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


An organism's decreasing response to a stimulus with repeated exposure to it


Cycles per second

Muller Lyer illusion

A famous visual illusion involving the misperception of the identical length of two lines, one with arrows pointed inward, one with arrows pointed outward.

olfactory bulbs

Area of the brain that processes information about smell; one bulb in each hemisphere


The outer ear that focuses sound waves for the middle and inner ears.

shape constancy

Perception that the actual shape of an object remains the same, even when it is seen from different points of view and so the image on the retina changes shape


A law of organization that says that objects that look similar tend to be grouped together when we perceive them.


A process by which one sense modality is described or characterized in terms of another, such as "a bright sound" or "a quiet color."

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