Chapter 3: Sensation and Perception – Key Vocabulary

Vocabulary flashcards covering major concepts, structures, theories, and phenomena from the Sensation and Perception lecture.

Sensation

Process by which sense‐organ receptors are activated, turning external stimuli into neural signals.

Perception

Interpretation and organization of sensory information into meaningful experiences.

Transduction

Conversion of physical energy from the environment into neural activity.

Sensory Receptors

Specialized neurons that respond to specific kinds of physical energy rather than neurotransmitters.

Synesthesia

Condition in which stimulation of one sense leads to automatic, involuntary experiences in a second sense.

Grapheme-Color Synesthesia

Form of synesthesia in which letters or numbers are consistently perceived as inherently colored.

Just Noticeable Difference (JND)

Smallest detectable difference between two stimuli, detected 50 % of the time.

Absolute Threshold

Minimum stimulus intensity that can be detected consciously 50 % of the time.

Supraliminal Stimulus

Stimulus intensity above the conscious detection threshold.

Subliminal Stimulus

Stimulus below the level of conscious awareness yet strong enough to activate receptors.

Subliminal Perception

Influence of subliminal stimuli on the unconscious mind and behavior.

Signal Detection Theory

Framework for measuring accuracy of decisions under uncertain sensory conditions.

Hit (SDT)

Correctly detecting a present stimulus.

False Alarm (SDT)

Incorrectly reporting a stimulus when none is present.

Miss (SDT)

Failing to detect a present stimulus.

Correct Rejection (SDT)

Correctly identifying that no stimulus is present.

Habituation

Brain’s decreasing response to constant, unchanging information.

Sensory Adaptation

Reduced receptor responsiveness to unchanging stimuli over time.

Microsaccades

Tiny involuntary eye movements that help prevent visual sensory adaptation.

Photon

Particle of light energy that travels in waves.

Wavelength (Light)

Distance between two successive light waves, determining color.

Intensity (Light)

Amplitude of light waves, determining brightness.

Saturation

Purity of a color; high saturation contains only one wavelength.

Cornea

Clear, curved surface of the eye that begins focusing light.

Iris

Pigmented muscle controlling pupil size.

Pupil

Opening in the iris through which light enters the eye.

Lens

Flexible structure that further focuses light onto the retina.

Retina

Layer of photoreceptor cells at the back of the eye where light is converted to neural signals.

Visual Accommodation

Automatic change in lens shape to focus on objects at various distances.

Presbyopia

Age-related loss of lens flexibility, reducing near focus ability.

Vitreous Humor

Jelly-like fluid filling the eyeball behind the lens, providing nourishment and shape.

Myopia

Nearsightedness; focal point falls short of the retina.

Hyperopia

Farsightedness; focal point is beyond the retina.

Duplexity Theory

Idea that vision relies on two receptor types, rods and cones, for different lighting conditions.

Rods

Photoreceptors specialized for dim light, peripheral vision, and low acuity.

Cones

Photoreceptors specialized for bright light, color vision, and high acuity, concentrated in the fovea.

Fovea

Central retinal area with highest visual acuity and only cones.

Blind Spot

Retinal area with no photoreceptors where the optic nerve exits the eye.

Optic Chiasm

X-shaped intersection where nasal retinal fibers cross to the opposite hemisphere.

Lateral Geniculate Nucleus (LGN)

Thalamic relay center for visual information en route to the cortex.

Trichromatic Theory

Color vision theory proposing three cone types sensitive to red, green, and blue wavelengths.

Opponent-Process Theory

Color vision theory proposing paired color channels (red–green, blue–yellow) with reciprocal activity.

Afterimage

Lingering visual impression that persists after the original stimulus is removed, supporting opponent theory.

Monochromatic Vision

Color-vision deficiency in which cones malfunction so only shades of gray are seen.

Dichromatic Vision

Color-vision deficiency due to one malfunctioning cone type, leaving two functional cones.

Protanopia

Red-green deficiency caused by non-functioning red cones.

Deuteranopia

Red-green deficiency caused by non-functioning green cones.

Tritanopia

Blue-yellow deficiency due to lack of blue cones.

Hertz (Hz)

Unit of sound frequency; one cycle per second.

Decibel (dB)

Unit measuring sound intensity or loudness.

Timbre

Quality or uniqueness of a sound determined by complexity of the wave.

Pinna

Visible outer ear structure that collects sound waves.

Auditory Canal

Tube leading from pinna to the eardrum.

Tympanic Membrane

Eardrum; thin membrane that vibrates with incoming sound.

Ossicles

Three middle-ear bones—hammer, anvil, stirrup—that amplify vibrations.

Cochlea

Fluid-filled, snail-shaped inner-ear structure where sound transduction occurs.

Organ of Corti

Sensory organ atop the basilar membrane housing hair cells.

Hair Cells

Receptor cells for hearing, bending to convert fluid movement into neural impulses.

Auditory Nerve

Bundle of axons carrying auditory information to the brain.

Place Theory

Pitch theory stating location of hair-cell stimulation on the basilar membrane codes frequency.

Frequency Theory

Pitch theory proposing basilar membrane vibrates at the same rate as the sound frequency.

Volley Principle

Theory that groups of neurons take turns firing to code intermediate frequencies (400–4 000 Hz).

Conductive Hearing Loss

Impaired sound conduction due to eardrum or ossicle damage.

Sensorineural Hearing Loss

Hearing impairment from inner-ear or auditory-pathway damage.

Cochlear Implant

Electronic device that converts sound to electrical signals stimulating the auditory nerve.

Gustation

Sense of taste.

Umami

Savory taste associated with glutamate; one of the five basic tastes.

Oleogustus

Proposed sixth basic taste for fatty acids.

Papillae

Small bumps on the tongue housing taste buds.

Gustatory Cortex

Brain region in the anterior insula and frontal operculum that processes taste.

Olfaction

Sense of smell.

Olfactory Bulbs

Brain structures above the nasal cavity receiving input from olfactory receptors.

Somesthetic Senses

Body senses including skin senses, kinesthetic sense, and vestibular senses.

Pacinian Corpuscles

Skin receptors responsive to changes in pressure.

Visceral Pain

Pain originating from internal organs.

Somatic Pain

Pain from skin, muscles, tendons, and joints.

Gate-Control Theory

Concept that pain signals pass through a ‘gate’ in the spinal cord that may be blocked or allowed.

Substance P

Neurotransmitter released by pain fibers to activate ascending pain pathways.

Endorphins

Endogenous opioids that inhibit pain by closing the spinal ‘gate.’

Congenital Analgesia

Rare disorder causing inability to feel pain.

Phantom Limb Pain

Perceived pain in a limb that has been amputated.

Kinesthesia

Awareness of body movement.

Proprioception

Sense of body-part position relative to each other and to the ground.

Vestibular Sense

Sense of head and body balance, position, and motion relative to gravity.

Sensory Conflict Theory

Explanation of motion sickness arising from mismatched visual and vestibular signals.

Size Constancy

Perception of an object as the same size regardless of distance.

Shape Constancy

Perception of a familiar object’s shape as constant despite changes on the retina.

Brightness Constancy

Perception of consistent brightness under varying lighting.

Figure-Ground Relationship

Tendency to separate visual scenes into a main object (figure) and background (ground).

Reversible Figure

Image in which figure and ground can switch back and forth.

Proximity (Gestalt)

Grouping principle that objects near each other are perceived together.

Similarity (Gestalt)

Grouping principle that similar-looking items are perceived as part of the same group.

Closure

Tendency to complete incomplete figures to form meaningful wholes.

Continuity

Perceiving continuous patterns instead of broken ones.

Contiguity

Perceiving events occurring close in time as related.

Common Region

Grouping items located within the same bounded area.

Element Connectedness

Grouping items that are physically linked, overriding similarity and proximity.

Depth Perception

Ability to perceive the world in three dimensions.

Linear Perspective

Monocular cue where parallel lines appear to converge in the distance.

Relative Size

Monocular cue where smaller objects are perceived as farther away.