Sensation & Perception – Vocabulary Review

A comprehensive set of vocabulary flashcards covering key terms, concepts, structures, theories, and processes related to sensation, perception, and attention as presented in the lecture notes.

Sensation

The immediate, direct experience produced when a stimulus activates a sense organ and is transduced into neural signals.

Perception

The cognitive process of selecting, organizing, and interpreting sensory information to create meaningful experience.

Stimulus

Any form of energy in the environment that activates sense receptors (e.g., light, sound, chemicals, mechanical pressure).

Sense Organ

Specialized anatomical structure (eye, ear, skin, tongue, nose) that receives specific stimuli from the environment.

Transduction

Conversion of physical stimulus energy into neural impulses by receptor cells.

Psychophysics

The scientific study of relationships between physical stimuli and the sensations and perceptions they produce.

Gustav Fechner

Psychologist who coined the term psychophysics and investigated sensory thresholds.

Absolute Threshold

The minimum intensity of a stimulus that can be detected 50 % of the time.

Differential Threshold (JND)

The smallest detectable difference between two stimuli; produces a just noticeable difference.

Adaptation (Sensory)

Decreased responsiveness of sensory receptors to constant, unchanging stimulation over time.

Dark Adaptation

Gradual increase in retinal sensitivity that occurs in low illumination as rods become more active.

Light Adaptation

Process by which the eye decreases sensitivity after moving to brighter conditions; cones dominate.

Rods

Retinal photoreceptors sensitive to low light, achromatic vision, and peripheral vision (≈120 million).

Cones

Retinal photoreceptors concentrated in the fovea; enable color vision and high acuity (≈7 million).

Cornea

Curved, transparent outer layer of the eye where light first enters and begins focusing.

Pupil

Adjustable opening in the center of the eye that regulates the amount of light entering.

Iris

Colored muscular ring that constricts or dilates the pupil to control light entry.

Lens

Transparent structure behind the pupil that changes shape to focus light on the retina.

Retina

Light-sensitive inner surface of the eye containing rods, cones, and neural layers that process visual information.

Fovea

Central focal point in the retina with highest concentration of cones and sharpest vision.

Blind Spot

Area of the retina where the optic nerve exits; contains no photoreceptors and is insensitive to light.

Bipolar Cells

Retinal neurons that receive input from rods and cones and transmit signals to ganglion cells.

Ganglion Cells

Retinal neurons whose axons form the optic nerve and convey visual information to the brain.

Optic Nerve

Bundle of ganglion-cell axons that carries visual impulses from the eye to the brain.

Optic Chiasm

X-shaped junction where half of optic-nerve fibers cross to the opposite hemisphere.

Lateral Geniculate Nucleus (LGN)

Relay nucleus in the thalamus that receives visual input from the optic tract and projects to visual cortex.

Primary Visual Cortex

Region of occipital lobe (V1) where basic visual processing occurs.

Duplicity Theory

Idea that rods mediate achromatic night vision while cones mediate chromatic daylight vision.

Trichromatic Theory

Young–Helmholtz proposal that three cone types (red, green, blue sensitive) combine to produce color vision.

Opponent Process Theory

Theory that color vision is governed by opposing neural processes (red-green, blue-yellow, black-white).

Nearsightedness (Myopia)

Condition where images focus in front of the retina; distant objects appear blurry.

Farsightedness (Hyperopia)

Condition where images focus behind the retina; close objects appear blurry.

Saccadic Movement

Rapid, jerky eye movement that abruptly changes the point of fixation.

Pursuit Movement

Smooth eye movement that follows a moving object.

Vergence Movement

Simultaneous inward or outward turning of eyes to maintain single vision of an object.

Sound Wave

Mechanical vibration of air molecules creating alternating compressions and rarefactions perceived as sound.

Amplitude (Sound)

Height of a sound wave; determines loudness.

Frequency (Sound)

Number of wave cycles per second (Hz); determines pitch.

Wavelength (Sound)

Distance between successive wave peaks; inversely related to frequency.

Pinna

Outer ear flap that collects and channels sound waves into the auditory canal.

Tympanic Membrane (Eardrum)

Thin membrane that vibrates in response to sound waves, transmitting them to the ossicles.

Ossicles

Three tiny middle-ear bones (malleus, incus, stapes) that amplify and transmit vibrations to the oval window.

Oval Window

Membrane at the entrance to the cochlea that receives ossicle vibrations.

Cochlea

Snail-shaped, fluid-filled inner-ear structure where sound transduction occurs.

Basilar Membrane

Membranous structure inside the cochlea that supports the organ of Corti and vibrates to sound.

Organ of Corti

Sensory organ atop the basilar membrane containing hair cells that transduce sound.

Hair Cells

Receptor cells of the inner ear that convert mechanical vibrations into neural impulses.

Auditory Nerve

Bundle of axons carrying auditory information from hair cells to the brain.

Place Theory

Pitch perception theory stating that different cochlear places vibrate maximally to different frequencies.

Frequency Theory

Pitch perception theory proposing that the entire basilar membrane vibrates at the same frequency as the sound.

Volley Principle

Concept that groups of neurons fire alternately to encode frequencies above the firing limit of single neurons.

Somesthesis

Collective term for skin senses such as touch, pressure, temperature, vibration, and pain.

Pacinian Corpuscle

Deep-skin receptor sensitive to rapid vibration and deep pressure.

Meissner Corpuscle

Superficial receptor specialized for light touch and texture.

Ruffini Cylinder

Skin receptor responding to sustained pressure and warmth.

Free Nerve Ending (Nociceptor)

Unencapsulated nerve fiber that detects pain and temperature changes.

Gate Control Theory

Melzack & Wall’s idea that a neural “gate” in the spinal cord modulates incoming pain signals.

Visceral Pain

Pain originating from internal organs, often referred to distant body surfaces.

Somatic Pain

Pain arising from skin, muscles, joints, or tendons; serves as body’s warning system.

Gustation

Sense of taste, stimulated by water-soluble chemicals acting on taste buds.

Papillae

Bumps on the tongue’s surface that house clusters of taste buds.

Taste Bud

Cluster of taste receptor cells embedded in papillae that detect sweet, sour, salty, bitter, and umami.

Umami

Fifth basic taste quality, triggered by glutamate; perceived as savory or meaty.

Olfaction

Sense of smell, stimulated by volatile chemical substances.

Olfactory Epithelium

Mucous membrane high in nasal cavity containing olfactory receptor cells.

Pheromone

Chemical signal released by an organism that affects behavior or physiology of others of the same species.

Bombykol

Sex pheromone emitted by female silkworm moths to attract males.

Kinesthetic Sense

Sense of body position and movement provided by receptors in muscles, tendons, and joints.

Stretch Receptor

Nerve ending in muscle fibers that signals muscle length changes.

Golgi Tendon Organ

Receptor at muscle–tendon junction that monitors tension and prevents overexertion.

Vestibular Sense

Sense of balance, body position, and acceleration derived from inner-ear structures.

Semicircular Canals

Three fluid-filled, curved tubes in the inner ear that detect rotational head movements.

Endolymph

Fluid inside semicircular canals whose motion stimulates vestibular hair cells.

Gestalt Principles

Innate rules describing how we organize sensory input into meaningful wholes.

Figure-Ground

Gestalt principle stating we separate visual field into a focused figure and a background.

Law of Similarity

Tendency to group similar elements together in perception.

Law of Proximity

Tendency to perceive objects that are close together as belonging to the same group.

Law of Closure

Tendency to fill in gaps and perceive incomplete figures as complete wholes.

Law of Continuation

Preference for continuous, smooth lines and patterns over discontinuous ones.

Law of Common Fate

Tendency to group elements moving in the same direction as a unit.

Perceptual Constancy

Stable perception of objects despite changes in sensory input.

Color Constancy

Perceiving familiar objects as having consistent color under differing illumination.

Size Constancy

Perception of an object’s true size despite changes in retinal image size.

Shape Constancy

Perception of a familiar object’s shape as constant despite viewing angle changes.

Illusion

Persistent perceptual misinterpretation of a real external stimulus.

Müller-Lyer Illusion

Visual illusion where arrow-headed lines of equal length appear different in size.

Ponzo Illusion

Illusion in which converging lines make identical objects appear different in size or distance.

Zollner Illusion

Pattern illusion where parallel lines appear to diverge due to short intersecting lines.

Ebbinghaus Illusion

Contextual size illusion where a circle’s perceived size depends on surrounding circles.

Horizontal-Vertical Illusion

Tendency to overestimate vertical lines relative to horizontal ones of equal length.

Depth Perception

Ability to perceive three-dimensional space and judge distance.

Monocular Cues

Depth cues available to each eye alone (e.g., linear perspective, texture gradient).

Linear Perspective

Depth cue in which parallel lines appear to converge with distance.

Motion Parallax

Depth cue where closer objects seem to move opposite and faster than distant ones while moving.

Retinal Disparity

Binocular depth cue arising from the difference between images in each eye.

Convergence (Depth Cue)

Degree to which eyes turn inward to focus on close objects, signaling distance.

Stereoscopic Vision

Depth perception resulting from the brain’s fusion of slightly different images from both eyes.

Looming

Rapid expansion of an image on the retina indicating an approaching object.

Autokinetic Effect

Perceived motion of a stationary point of light in darkness due to eye movements and lack of cues.

Stroboscopic Motion

Illusion of motion produced by rapid presentation of a series of still images (basis of movies).