Unit 3 vocab - Sensation and Perception

Sensation

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

Transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.

absolute threshold

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

just noticeable difference (JND)

the minimal change in a stimulus that can just barely be detected

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

Weber's Law

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

sensory interaction

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

Synesthesia

describing one kind of sensation in terms of another ("a loud color", "a sweet sound")

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

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

lens

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

accomadation

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

nearsightedness

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

Farsightedness

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

Photoreceptors

respond to light

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.

trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

Afterimages

images that occur when a visual sensation persists for a brief time even after the original stimulus is removed

Ganglion cells

In the retina, the specialized neurons that connect to the bipolar cells; the bundled axons of the ganglion cells form the optic nerve.

Dichromatism

A type of color blindness where one of the three basic color mechanisms is absent or not functioning.

Monochromatism

the inability to distinguish colors; also known as color blindness

Prosopagnosia

inability to recognize faces

Blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

pitch

a tone's experienced highness or lowness; depends on frequency

Amplitude

Height of a wave

Loudness

A physical response to the intensity of sound, modified by physical factors

pitch perception

the aspect of hearing that allows us to tell how high or low a given tone is

place theory

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

volley theory

the view that some sounds are coded by matching the frequency of neural firing

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

sound localization

the process by which the location of sound is determined

conduction deafness

An inability to hear resulting from damage to structures of the middle or inner ear.

sensorineural deafness

deafness that results from damage to the auditory nerve

olfactory system

the sensory system for smell

Thalamus

the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Pheromones

odorless chemicals that serve as social signals to members of one's species

Gustation

sense of taste

Taste (Sweet, Sour, Salty, Bitter & Umami)

sweet can indicate energy (carbohydrates), salty indicates essential salts, sour and bitter can signal potential toxicity, and umami (a savory taste) signals the presence of protein.

taste receptors

chemical receptors on the tongue that decode molecules of food or drink to identify them

Supertasters

people with heightened sensitivity to all tastes and mouth sensations

medium tasters

Have an average sensitivity to taste, experiencing flavors moderately.

Nontasters

people who cannot detect bitter compounds except at very high concentrations

gate-control theory

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

vestibular sense

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

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement

kinesthesis

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

bottom-up processing

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

top-down processing

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

Schema

a concept or framework that organizes and interprets information

perceptual set

a mental predisposition to perceive one thing and not another

Gestalt psychologists

a group of psychologists who proposed principles governing perception, such as laws of organization, and a perceptual approach to problem solving involving restructuring

Closure

the tendency to complete figures that are incomplete

figure and ground

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

Proximity

Proximity affects the perception of an object because if looking at a group of objects and some of them seem smaller, this would make them appear farther away from you.

similarity

the tendency to perceive things that look similar to each other as being part of the same group

attention

focusing awareness on a narrowed range of stimuli or events

selective attention

the focusing of conscious awareness on a particular stimulus

cocktail party effect

ability to attend to only one voice among many

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment

binocular depth cues

clues about distance based on the differing views of the two eyes

retinal disparity

the differences between the images stimulating each eye

convergence

A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object

monocular depth cues

aspects of a scene that yield information about depth when viewed with only one eye

relative clarity

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

relative size

a monocular cue for perceiving depth; the smaller retinal image is farther away

texture gradient

a monocular cue for perceiving depth; a gradual change from a coarse distinct texture to a fine, indistinct texture signals increasing distance. objects far away appear smaller and more densely packed

linear perspective

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

Interposition

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

apparent movement

the perception that a stationary object is moving