Sensation, Perception, and Psychophysics

A complete set of 52 vocabulary flashcards covering sensation, psychophysics, anatomy of vision, auditory processes, other sensory systems, and principles of perception.

Absolute threshold

The minimum intensity of a stimulus required for a person to detect it $50\%$ of the time.

Transduction

The biological process of converting physical energy (like light or sound waves) into electrical neural signals.

Just noticeable difference (JND)

The smallest change or difference between two stimuli that a person can detect $50\%$ of the time.

Subliminal

Any sensory stimulus that falls below an individual's absolute threshold for conscious awareness.

Sensory adaptation

A decrease in sensitivity to a constant, unchanging stimulus over time (e.g., getting used to a cold pool).

Weber’s law

The principle stating that to be perceived as different, two stimuli must differ by a constant minimum percentage rather than a fixed amount.

Synesthesia

A neurological condition where the stimulation of one sensory pathway leads to involuntary experiences in a second sensory pathway (e.g., "tasting" words or "seeing" music).

Retina

The light-sensitive inner lining at the back of the eye containing photoreceptor cells.

Blind spot

The point on the retina where the optic nerve leaves the eye, containing no photoreceptor cells.

Visual (optic) nerve

The nerve bundle that carries neural impulses from the eye's retina directly to the brain.

Photoreceptors

Specialized neurons in the retina (rods and cones) that convert light energy into neural signals.

Rods

Photoreceptors that detect black, white, and gray; essential for peripheral and night vision.

Cones

Photoreceptors concentrated near the center of the retina that detect fine detail and color in daylight.

Lens

The transparent, flexible structure behind the pupil that changes shape to focus light onto the retina.

Accommodation

The process by which the eye’s lens changes its curvature and thickness to focus on near or distant objects.

Nearsightedness (Myopia)

A condition where close objects are seen clearly, but distant objects appear blurry because light focuses in front of the retina.

Farsightedness (Hyperopia)

A condition where distant objects are seen clearly, but close objects appear blurry because light focuses behind the retina.

Fovea

The central focal point in the retina around which the eye's cones cluster, providing the sharpest vision.

Ganglion cells

Neurons in the retina whose axons gather together to form the optic nerve.

Dichromatism

A type of color blindness where an individual only has two functioning types of cone receptors.

Monochromatism

A rare form of color blindness where a person has no functional cones (or only one type), seeing the world strictly in black, white, and shades of gray.

Prosopagnosia

A neurological disorder characterized by the inability to recognize familiar faces; also known as face blindness.

Blindsight

A condition in which people who are blind due to damage to the visual cortex can still respond to visual stimuli without consciously seeing them.

Trichromatic theory

The theory that the retina contains three types of color receptors (red, green, and blue) that combine to produce the perception of any color.

Opponent-process theory

The theory that color vision depends on three sets of opposing retinal processes (red-green, yellow-blue, white-black).

Place theory

The theory that links the pitch we hear with the specific place where the cochlea's membrane is stimulated.

Volley theory

The theory that groups of auditory nerve fibers fire neural impulses in rapid succession (volleys) to signal higher-pitched sounds.

Frequency theory

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

Conduction deafness

Hearing loss caused by mechanical damage to the physical structures that conduct sound waves to the cochlea (e.g., eardrum, tiny ear bones).

Sensorineural deafness

Hearing loss caused by damage to the cochlea's receptor cells (hair cells) or the auditory nerves; also known as nerve deafness.

Pheromones

Chemical signals released by an animal or human that communicate information to and affect the behavior or physiology of others of the same species.

Gustation

The chemical sense of taste.

Olfaction

The chemical sense of smell.

Gate control theory

The theory that the spinal cord contains a neurological "gate" that either blocks pain signals or allows them to pass onward to the brain.

Phantom limb syndrome

The sensation that an amputated or missing limb is still attached and moving, often accompanied by pain.

Vestibular sense

The sensory system that provides information about spatial orientation, balance, and head movement, originating in the inner ear.

Semicircular canals

Three fluid-filled tubes in the inner ear that detect rotational movements of the head to help maintain balance.

Kinesthesis

The system for sensing the position and movement of individual body parts through receptors in muscles, tendons, and joints.

Top-down processing

Information processing guided by higher-level mental processes, drawing on our expectations, memories, and experiences to interpret sensory data.

Bottom-up processing

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

Perceptual sets

A mental predisposition or readiness to perceive something in a particular way based on expectations, assumptions, or prior experience.

Gestalt psychology

A psychological approach emphasizing that we inherently organize sensory information into meaningful wholes ("the whole is greater than the sum of its parts").

Figure/ground

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

Selective attention

The focusing of conscious awareness on a particular stimulus while filtering out other competing stimuli.

Cocktail party effect

The ability to focus one's auditory attention on a single conversation in a noisy room while still subconsciously monitoring for personally relevant words like your own name.

Inattentional blindness

Failing to see visible objects when our attention is directed elsewhere.

Change blindness

Failing to notice environmental changes happening right in front of us (often masked by a brief visual interruption).

Binocular depth cues

Depth information that requires the coordinated use of both eyes (e.g., retinal disparity).

Monocular depth cues

Depth information available to each eye alone (e.g., relative size, interposition).

Retinal disparity

A binocular cue for perceiving depth based on the slightly different images received by each retina because our eyes are a few inches apart.

Interposition

A monocular cue where an object that partially blocks our view of another object is perceived as closer.

Linear perspective

A monocular cue where parallel lines appear to converge or meet in the distance.