AP Psych - Sensation and Perception Terms

Sensation

The process by which sensory receptors detect and send stimuli from the environment to the brain.

Absolute Threshold

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

Transduction

The conversion of sensory energy (like light or sound) into neural impulses the brain can interpret.

Just-Noticeable Difference (JND)

The smallest change in a stimulus that can be detected 50% of the time.

Sensory Adaptation

Decreased sensitivity to a constant, unchanging stimulus over time.

Weber’s Law

The principle that two stimuli must differ by a constant proportion to be perceived as different.

Sensory Interaction

When one sense influences another (e.g., smell affects taste).

Synesthesia

A condition in which stimulation of one sense leads to automatic experiences in another (e.g., seeing colors when hearing music).

Retina

The light-sensitive layer of cells at the back of the eye that contains rods and cones.

Blind Spot

The area on the retina where the optic nerve leaves the eye—no receptor cells are located there.

Optic Nerve

The nerve that carries visual information from the retina to the brain.

Lens

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

Accommodation

The process by which the lens changes shape to focus on near or distant objects.

Rods

Retinal receptors that detect black, white, and gray; used for peripheral and night vision.

Cones

Retinal receptors concentrated in the fovea that detect color and fine detail.

Fovea

The central focal point of the retina where cones are concentrated.

Trichromatic Theory

The theory that color vision results from the activity of three cone types: red, green, and blue.

Opponent Process Theory

The theory that color perception depends on opposing pairs (red-green, blue-yellow, black-white). Explains afterimages.

Afterimages

Visual sensations that remain after the stimulus is removed, due to opponent color processing.

Ganglion Cells

Neurons in the retina that receive input from bipolar cells and form the optic nerve.

Dichromatism

Color blindness resulting from one malfunctioning cone system (usually red-green or blue-yellow).

Monochromatism

Total color blindness; only one type of cone or none works properly.

Prosopagnosia

“Face blindness”; inability to recognize faces.

Blindsight

Ability of blind individuals with brain damage to respond to visual stimuli without consciously seeing them.

Pitch

A tone’s highness or lowness, determined by frequency.

Amplitude

Height of a sound wave; determines loudness.

Place Theory

Theory that different sound frequencies stimulate different places on the cochlea’s basilar membrane.

Volley Theory

Groups of neurons alternate firing to achieve higher frequencies than one could alone.

Frequency Theory

The idea that the rate of nerve impulses matches the frequency of a tone, enabling perception of pitch.

Sound Localization

The ability to determine the direction and distance of a sound source.

Conduction Deafness

Hearing loss caused by damage to the mechanical system (eardrum or ossicles) that conducts sound waves.

Sensorineural Deafness

Hearing loss from damage to the cochlea’s hair cells or auditory nerve.

Vestibular Sense

The sense of body balance and spatial orientation, located in the inner ear.

Semicircular Canals

Three fluid-filled canals in the inner ear that detect head rotation and help with balance.

Kinesthetic Sense

The sense of body position and movement of body parts.

Perception

The process of organizing and interpreting sensory information.

Bottom-Up Processing

Analysis that begins with the sensory receptors and works up to the brain’s integration.

Top-Down Processing

Information processing guided by experience, expectations, and prior knowledge.

Schemas

Mental frameworks that help organize and interpret information.

Perceptual Sets

A mental predisposition to perceive something a certain way based on expectations.

Context Effects

How the environment or situation influences perception.

Gestalt

The whole is greater than the sum of its parts; principles that explain how we group sensory information.

Closure

The tendency to fill in gaps in incomplete figures to see them as complete.

Figure-Ground

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

Proximity

The tendency to group nearby objects together.

Similarity

The tendency to group similar items together.

Selective Attention

Focusing conscious awareness on a particular stimulus.

Cocktail Party Effect

Ability to focus on one voice among many and detect your name in a noisy environment.

Change Blindness

Failure to notice large changes in one’s visual field.

Binocular Cues

Depth cues that depend on using both eyes.

Retinal Disparity

The difference between the two eyes’ images, used to perceive depth.

Convergence

The inward turning of the eyes when focusing on a close object; a depth cue.

Monocular Cues

Depth cues available to each eye alone.

Relative Clarity

Hazy objects are perceived as farther away.

Relative Size

Smaller images are perceived as farther away if objects are known to be similar in size.

Texture Gradient

Texture becomes less detailed as distance increases.

Linear Perspective

Parallel lines appear to converge with distance.

Interposition

When one object overlaps another, it is perceived as closer.

Perceptual Constancies

Perceiving objects as unchanging (color, shape, size) even when the image changes.

Apparent Movement

Perceiving motion when none exists (e.g., the phi phenomenon or motion pictures).

Inattentional Blindness

Failure to notice a fully visible, but unexpected, object or event when attention is directed elsewhere.