Chapter Five - Knapp 2000

sensation

Detection of physical energy by sense organs that relays information to the brain.

perception

The brain's interpretation of raw sensory inputs.

transduction

The process by which the nervous system converts an external stimulus into electrical signals.

sense receptor

Specialized cells responsible for converting external stimuli into neural activity for a specific sensory system.

sensory adaptation

Activation is greatest when a stimulus is first detected; awareness of a stimulus decreases with continued exposure.

psychophysics

The study of how we perceive sensory stimuli based on their physical characteristics.

absolute threshold

The lowest level of a stimulus needed for the nervous system to react.

just noticeable difference

The smallest change in the intensity of a stimulus that we can detect.

Weber's law

There is a constant proportional relationship between the just noticeable difference and the original stimulus intensity.

selective attention

The process of selecting one sensory channel to focus on while ignoring others.

filter theory of attention

Views attention as a bottleneck through which information passes, allowing us to focus on important stimuli.

cocktail party effect

Our ability to pick out an important message in a conversation that doesn’t involve us.

inattentional blindness

Failure to detect stimuli that are in plain sight when our attention is focused elsewhere.

change blindness

Failure to detect obvious changes in one's environment.

binding problem

The issue of how the unity of conscious perception arises from distributed activities of the central nervous system.

light

Electromagnetic radiation within the portion of the electromagnetic spectrum that can be perceived by the human eye.

visible light

Light usually defined as having wavelengths in the range of 400-700 nanometers.

sclera

The white outer layer of the eyeball.

iris

The colored part of the eye that controls the amount of light entering.

pupil

The circular hole that light enters the eye through.

cornea

Part of the eye that contains transparent cells focusing light on the retina.

accommodation

The process by which the lenses change shape to focus light on the retina.

nearsightedness

A condition where images are focused in front of the retina.

farsightedness

A condition where images are focused behind the retina.

retina

The membrane at the back of the eye converting light into neural activity.

fovea

The central portion of the retina responsible for sharp vision.

acuity

Sharpness of vision.

rods

Photoreceptors enabling us to see basic shapes and forms in low light.

cones

Photoreceptors that provide color vision.

dark adaptation

The time taken for rods to regain maximum light sensitivity in the dark.

ganglion cells

Cells in the retinal circuit that send visual information to the brain via the optic nerve.

optic nerve

Nerve that transmits visual information from the retina to the brain.

blind spot

The area on the retina where the optic nerve exits and contains no rods or sense receptors.

trichromatic theory

The theory that color vision is based on sensitivity to three primary colors: blue, green, and red.

opponent-process theory

The theory that we perceive colors through three pairs of opponent colors.

pitch

The frequency of the sound wave, determining how high or low a sound is.

loudness

The perception of sound intensity, correlated with the amplitude of sound waves.

timbre

Complexity or quality of sound that allows us to distinguish different instruments or voices.

pinna

The visible part of the outer ear.

ear canal

Funnels sound waves into the eardrum.

ossicles

Three tiny bones in the middle ear that transmit sound from the eardrum to the inner ear.

cochlea

Spiral-shaped sense organ in the inner ear that converts vibration into neural activity.

organ of corti

Tissue in the cochlea that contains hair cells necessary for hearing.

basilar membrane

Membrane supporting the organ of corti in the cochlea.

place theory

Theory that pitch is determined by the specific location of stimulation on the basilar membrane.

frequency theory

The theory that pitch is determined by the rate at which neurons fire action potentials.

ventral stream

Pathway in the brain associated with processing the 'what' of visual information.

dorsal stream

Pathway in the brain associated with processing the 'where' of visual information.

olfaction

The sense of smell.

gustation

The sense of taste.

taste buds

Sensory receptors in the tongue responsible for all tastes.

parallel processing

The ability to attend to multiple sensory modalities simultaneously.

bottom-up processing

Processing that begins with raw sensory data and builds up to a cohesive perception.

top-down processing

Processing that starts with expectations and beliefs that influence perception.

perceptual constancy

The ability to perceive objects as unchanging despite changes in sensory input.

gestalt principles

Principles that govern how we perceive objects as unified wholes.

proximity

The principle that objects close to each other are perceived as a group.

similarity

The principle that we perceive similar objects as belonging together.

continuity

The principle that we perceive continuous patterns rather than disjointed ones.

closure

The principle that our minds fill in gaps in visual information.

symmetry

The principle that we perceive symmetrical objects as wholes.

figure-ground

The principle that distinguishes between the main object and the background.

depth perception

The ability to judge distance and spatial relationships.

binocular depth cues

Depth cues that require both eyes to perceive depth.

monocular depth cues

Depth cues that can be perceived with one eye.

binocular disparity

The difference in images between our two eyes to perceive depth.

binocular convergence

The inward turning of the eyes when focusing on nearby objects.