Chapter 5 Ultimate

just noticeable difference

The smallest change in stimulus intensity that a person can reliably detect 50% of the time

absolute threshold

The lowest level of a stimulus intensity that can be detected half the time

sensory adaptation

A decrease in sensitivity to a constant stimulus over time

transduction

The conversion of physical energy (like light or sound) into neural signals

sensation

The process by which sensory receptors detect and respond to stimuli

perception

The brain’s interpretation and organization of sensory information

pupil

The opening in the center of the iris that controls how much light enters the eye

iris

The colored muscular ring around the pupil that adjusts its size to regulate light entry

lens

The transparent structure behind the pupil that focuses incoming light onto the retina

presbyopia

Age-related loss of the eye’s ability to focus on close objects

retina

The light-sensitive layer at the back of the eye where photoreceptors convert light into signals

fovea

The small central pit in the retina responsible for sharp central vision

rods

Photoreceptors in the retina that detect low light levels and aid peripheral vision

cones

Photoreceptors in the retina that detect color and detail in brighter light

ganglion cells

Neurons in the retina that collect input from photoreceptors and send it to the brain

blind spot

The point on the retina where the optic nerve exits the eye, creating a gap in vision

optic nerve

The bundle of nerve fibers that carries visual information from the retina to the brain

opponent-process theory

A color vision theory proposing that colors are perceived through opposing pairs (red–green, blue–yellow)

trichromatic theory

A theory stating that color vision is based on three types of cones sensitive to red, green, and blue light

auditory canal

The tube through which sound waves travel to reach the eardrum

oval window

The membrane-covered opening between the middle ear and the cochlea that transfers sound vibrations

basilar membrane

The structure inside the cochlea that vibrates in response to sound, stimulating hair cells

cochlea

The spiral, fluid-filled inner ear structure that converts sound vibrations into neural impulses

eardrum (tympanic membrane)

The membrane that vibrates when struck by sound waves, initiating the hearing process

semicircular canals

Three fluid-filled tubes in the inner ear that detect head rotations and help maintain balance

place coding

The principle that different sound frequencies stimulate different locations along the basilar membrane

vestibular sense

The sense of body movement and balance, arising from receptors in the inner ear

gustation

The sensory experience of taste

taste buds

Clusters of sensory cells on the tongue that detect chemicals and transmit taste information

olfaction

The sensory experience of smell

olfactory bulb

The brain structure that receives smell information from the nose and processes it

gate-control theory

A theory suggesting that spinal cord “gates” can block or allow pain signals to reach the brain

kinesthetic sense

The awareness of body position and movement based on feedback from muscles and joints

size/shape constancy

The perception that an object’s size and shape remain the same despite changes in the retinal image

figure-ground

The perceptual ability to distinguish an object (the figure) from its background (the ground)

stroboscopic motion

The illusion of smooth movement created by rapidly presenting a series of still images

convergence

A binocular depth cue based on the inward angle of the eyes when focusing on a close object

binocular disparity

The slight difference between the two eyes’ views that the brain uses to perceive depth

monocular depth perception

Depth cues available with one eye, such as relative size, interposition, and texture gradien