Ap Psych 1.6 and 2.1

Absolute threshold

Minimum stimulus intensity detected $50\%$ of the time.

Difference threshold

Minimum difference between two stimuli detected $50\%$ of the time.

Just noticeable difference

Smallest detectable difference between two stimuli.

Sensation

Detecting physical environmental energy through sensory receptors.

Sensory adaptation

Decreased sensitivity resulting from constant, unchanging stimulation.

Sensory interactions

Principle that one sense may influence another.

Signal detection theory

Model predicting how and when a faint stimulus is detected amid background stimulation, based on sensitivity and psychological state.

Synesthesia

Phenomenon in which stimulation of one sensory pathway involuntarily triggers experiences in another.

Transduction

Conversion of physical stimuli into neural signals that the brain can process.

Weber's law

Principle that to be perceived as different, two stimuli must differ by a constant minimum proportion rather than a fixed amount.

Accommodation

Process by which the eye's lens alters its shape to focus images on the retina.

Afterimage

Visual impression that remains in perception after the stimulus has disappeared.

Blind spot

Area of the retina where the optic nerve exits, lacking photoreceptor cells.

Blindsight

Condition in which an individual responds to visual stimuli without conscious awareness of seeing them.

Color blindness

Deficiency in distinguishing certain hues due to absent or malfunctioning cone pigments.

Cones

Retinal photoreceptors clustered near the fovea that function in daylight and detect fine detail and hues.

Dark adaptation

Gradual increase in visual sensitivity occurring when entering low-light conditions.

Dichromatism

Form of color deficiency characterized by having only two functional cone types.

Farsightedness

Visual condition in which light focuses behind the retina, causing nearby objects to appear blurry.

Fovea

Central focal area of the retina containing a high density of cones, providing the sharpest visual acuity.

Hue

Dimension of color determined by the wavelength of light.

Monochromatism

Complete color deficiency resulting from having only one or no functional cone types.

Nearsightedness

Visual condition in which light focuses in front of the retina, causing distant objects to appear blurry.

Opponent-process theory

Theory proposing that color vision relies on opposing retinal systems: red-green, yellow-blue, and white-black.

Optic chiasm

X-shaped anatomical structure where fibers of the optic nerves partially cross over to the opposite side of the brain.

Optic nerve

Nerve bundle carrying neural impulses from the retina to the brain.

Photoreceptor

Specialized light-sensitive cell (rod or cone) in the retina that converts light into electrical signals.

Prosopagnosia

Neurological inability to recognize familiar human faces despite intact general vision.

Retina

Light-sensitive neural layer lining the back inside surface of the eye.

Rods

Retinal photoreceptors sensitive to dim light and peripheral movement, incapable of color detection.

Trichromatic theory

Theory asserting that color vision relies on three distinct cone types maximally sensitive to red, green, or blue wavelengths.

Wavelength

Distance between successive wave peaks; determines hue in light and pitch in sound.

Amplitude

Height of a wave; determines the perceived loudness of sound or brightness of light.

Audition

Sense or physiological act of hearing.

Conduction deafness

Hearing loss caused by mechanical failure in the outer or middle ear structures that transmit vibrations.

Frequency

Number of wave cycles per second; determines perceived pitch.

Frequency theory

Theory proposing that pitch is encoded by the rate of nerve impulses traveling up the auditory nerve.

Nerve deafness

Hearing impairment caused by damage to the cochlea's hair cell receptors or auditory pathways.

Pitch

Perceived auditory quality of sound's highness or lowness, determined by wave frequency.

Place theory

Theory linking perceived pitch to the specific location stimulated along the cochlea's basilar membrane.

Sensorineural deafness

Hearing loss caused by damage to the inner ear's receptor cells or auditory nerve fibers.

Sound localization

Ability to identify the direction and distance of an acoustic source using time and intensity differences between ears.

Volley theory

Principle stating that clusters of neurons alternate firing in rapid succession to encode frequencies above $1000\,\text{Hz}$.

Bitter

Taste modality typically triggered by potentially toxic alkaloids and plant poisons.

Chemical sense

Sensory system, such as gustation or olfaction, that transduces environmental molecules into neural impulses.

Gustation

Sensory system responsible for the perception of taste.

Medium taster

Individual possessing an average density of taste buds and standard flavor sensitivity.

Nontaster

Individual possessing a low density of taste buds and reduced sensitivity to flavor compounds.

Oleogustus

Proposed taste modality specialized in detecting non-esterified fatty acids.

Olfaction

Sensory system responsible for the sense of smell.

Pheromone

Airborne chemical compound released by an animal that influences the behavior or physiology of conspecifics.

Salty

Taste modality stimulated primarily by sodium chloride and other mineral cations.

Sour

Taste modality triggered by hydrogen ions present in acidic substances.

Supertaster

Individual possessing a high density of fungiform papillae, resulting in heightened taste sensitivity.

Sweet

Taste modality stimulated by simple sugars and related energy-rich compounds.

Umami

Savory taste sensation elicited by glutamate and certain amino acids.

Gate control theory

Model proposing that spinal cord neurological mechanisms regulate which pain signals reach the brain.

Kinesthesis

Proprioceptive awareness of the position and movement of individual body parts.

Kinesthetic sense

System that provides feedback regarding muscle tension, joint angle, and bodily movement.

Phantom limb pain

Painful sensations perceived as originating from an amputated or absent body part.

Vestibular sense

Sensory system centered in the inner ear that monitors balance, equilibrium, and head movement.

Apparent movement

Illusion of motion perceived when stationary images are presented in rapid succession.

Attention

Cognitive process of focusing mental awareness on specific stimuli or information.

Binocular depth cues

Distance and depth indicators that rely on the coordinated input of both eyes.

Bottom-up processing

Information processing that begins with raw sensory inputs and builds upward to conceptual understanding.

Change blindness

Perceptual failure to notice alterations in an environment or visual scene.

Closure

Gestalt grouping principle of filling in gaps to perceive an incomplete figure as a unified whole.

Cocktail party effect

Ability to selectively attend to a single conversation amid a noisy auditory environment.

Cognition

Mental activities associated with thinking, knowing, remembering, and processing information.

Context

Surrounding environmental cues that influence how incoming sensory stimuli are perceived.

Convergence

Neuromuscular binocular cue in which the eyes rotate inward to focus on near objects.

Cultural expectations

Socially learned beliefs and practices that guide how sensory stimuli are interpreted.

Depth perception

Ability to perceive spatial distance and see objects in three dimensions.

Expectations

Prior mental assumptions and predictions that shape the interpretation of incoming stimuli.

External sensory information

Incoming physical signals from the environment detected by peripheral receptors.

Figure-ground perception

Organization of the visual field into distinct objects standing out from their background.

Gestalt psychology

School of thought emphasizing the mind's tendency to organize individual sensations into meaningful wholes.

Grouping

Perceptual tendency to organize sensory features into coherent patterns or units.

Inattentional blindness

Failing to see visible objects when conscious attention is focused elsewhere.

Internal prior expectations

Stored knowledge, past experiences, and memories that guide top-down interpretation of stimuli.

Interposition

Monocular depth cue in which an object that partially blocks another is perceived as closer.

Linear perspective

Monocular depth cue in which parallel lines appear to converge as they recede into the distance.

Monocular depth cues

Distance cues available to either eye operating independently.

Perception

Process of organizing and interpreting sensory information to recognize meaningful objects and events.

Perceptual constancy

Perceiving objects as unchanging in size, shape, and color despite variations in retinal images.

Perceptual set

Mental predisposition to perceive certain aspects of sensory data while ignoring others.

Proximity

Gestalt grouping principle stating that objects positioned close together are seen as belonging together.

Relative clarity

Monocular depth cue in which clearer objects are perceived as closer than hazy, blurred ones.

Relative size

Monocular depth cue in which the smaller of two similar objects is judged to be farther away.

Retinal disparity

Binocular depth cue resulting from the slightly different images cast onto the left and right eyes.

Schema

Cognitive framework or mental blueprint that organizes and interprets information.

Selective attention

Focusing conscious awareness on a particular stimulus while filtering out irrelevant inputs.

Selective inattention

Failure to perceive or process sensory information outside the immediate focus of attention.

Similarity

Gestalt grouping principle stating that items sharing visual features are perceived as part of the same group.

Texture gradient

Monocular depth cue where surface detail appears progressively finer and denser at greater distances.

Top-down processing

Information processing guided by higher-level mental functions, expectations, and prior knowledge.

Visual perceptual processes

Brain mechanisms that interpret optical signals into unified impressions of shape, depth, and motion.