Psychology Sensation and Perception: Vision, Hearing, Taste, and Pain

Sensation

Detecting physical energy from the environment through sensory receptors.

Transduction

Converting stimulus energy into neural signals the brain can process.

Absolute threshold

The minimum stimulation detected 50 percent of the time.

Just-noticeable difference

The smallest difference between two stimuli detected 50 percent of the time.

Sensory adaptation

Reduced sensitivity to a constant, unchanging stimulus over time.

Weber's law

A detectable difference is a constant proportion of the original stimulus intensity.

Sensory interaction

The influence of one sense on another, such as smell affecting taste.

Synesthesia

A condition in which stimulation of one sense automatically evokes another sensory experience.

Retina

The light-sensitive layer at the back of the eye that contains photoreceptors.

Blind spot

The retinal location where the optic nerve exits and no photoreceptors are present.

Visual nerve

The optic nerve; carries visual signals from the retina toward the brain.

Lens

The transparent eye structure that changes shape to focus light on the retina.

Accommodation

The lens changing shape to focus on objects at different distances.

Nearsightedness

A focusing problem in which distant objects look blurry because light focuses before the retina.

Farsightedness

A focusing problem in which light tends to focus behind the retina, often blurring near objects.

Photoreceptors

Light-detecting retinal cells that convert light into neural signals.

Rods

Retinal receptors supporting dim-light and peripheral vision, but not color vision.

Cones (blue

green, red), Retinal receptors for color and detail; types are most sensitive to short, medium, or long wavelengths.

Trichromatic theory

Color vision begins with the combined activity of three types of cones.

Opponent-process theory

Color is processed in opposing channels: red-green, blue-yellow, and light-dark.

Afterimages

Visual sensations that persist after a stimulus is removed, often in complementary colors.

Ganglion cells

Retinal neurons whose axons form the optic nerve and carry signals toward the brain.

Dichromatism

Color vision based on two functioning cone types instead of three.

Monochromatism

Vision with no color discrimination, using one cone type or only rods.

Prosopagnosia

Difficulty recognizing familiar faces despite being able to see them.

Blindsight

Responding to visual stimuli without conscious awareness after damage to the primary visual cortex.

Wavelength

The distance between corresponding points on successive waves, such as crest to crest.

Pitch

The perceived highness or lowness of a sound, mainly related to frequency.

Amplitude

The maximum displacement of a wave from its resting level; relates to intensity.

Loudness

The perceived intensity of a sound, influenced mainly by wave amplitude.

Pitch perception

The process of judging how high or low a sound is using neural timing and cochlear location.

Place theory

Pitch depends on where vibration is strongest along the cochlea's basilar membrane.

Volley theory

Groups of auditory neurons alternate firing so their combined timing represents sound frequency.

Frequency theory

Pitch is coded by neural firing that follows a sound wave's frequency, especially at low frequencies.

Sound localization

Identifying a sound's source using cues such as timing and intensity differences between the ears.

Conduction deafness

Hearing loss caused by impaired sound transmission through the outer or middle ear.

Sensorineural deafness

Hearing loss caused by damage to inner-ear hair cells or the auditory nerve.

Olfactory system

The receptors and neural pathways responsible for the sense of smell.

Thalamus

A brain structure that relays most sensory information to the cortex; smell initially bypasses it.

Pheromones

Chemical signals released by an animal that affect others of its species; human effects remain unconfirmed.

Gustation

The sense of taste.

Sweet

sour, salty, bitter, umami, The five basic taste qualities; umami is the savory taste associated with glutamate.

Taste receptors

Sensory cells in taste buds that detect dissolved chemicals and initiate taste signals.

Supertasters

People unusually sensitive to certain tastes, especially bitter compounds such as PROP.

Medium tasters

People with intermediate sensitivity to bitter test compounds such as PROP.

Nontasters

People with little or no sensitivity to bitter test compounds such as PROP, not to all tastes.

Sensory interaction

The influence of one sense on another, such as smell affecting taste.

Warm/cold receptors

Temperature-sensitive nerve endings that detect warming or cooling of the skin.

Gate control theory

Spinal cord mechanisms can reduce or increase pain signals, influenced by touch and brain activity.

Phantom limb

The feeling that an amputated or missing limb is still present, sometimes with pain.

Vestibular sense

The sense of balance and head movement, based on structures in the inner ear.

Semicircular canals

Three fluid-filled inner-ear canals that detect rotational movements of the head.

Kinesthesis

The sense of body-part position and movement based on signals from muscles, tendons, and joints.