Psychology- Ch. 4- Sensation and perception- key terms

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

bottom-up processing

taking basic information about incoming sensory stimuli and processing it for further interpretation

top-down processing

drawing on past experiences and knowledge to understand and interpret sensory information

transduction

The process of converting outside stimuli, such as light, into neural activity

absolute threshold

the minimum stimulation needed to detect a particular stimulus 50 percent of the time

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time

webers law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

signal detection theory

a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and alertness.

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

hue

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

Amplitude

Height of a wave

saturation

purity of color

Cornea

The clear tissue that covers the front of the eye

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

Retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

Photoreceptors

specialized cells in the retina that absorb light energy and turn it into electrical and chemical signals for the brain to process

Rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

optic nerve

the nerve that carries neural impulses from the eye to the brain

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

dark adaptation

time in dark before rods regain maximum light sensitivity

light adaptation

the recovery of the eye's sensitivity to visual stimuli in light after exposure to darkness

feature detectors

nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green

Afterimage

A visual image that persists after a stimulus is removed.

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

audition

the sense or act of hearing

pitch

a tone's experienced highness or lowness; depends on frequency

Frequency

the number of complete wavelengths that pass a point in a given time

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

place theory

in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated

frequency theory

in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

volley principle

The theory holding that groups of auditory nerve fibers fire neural impulses in rapid succession, creating volleys of impulses.

Olfaction

sense of smell

Gustation

sense of taste

gate-control theory

the theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.

kinesthesia

sensory system that conveys information about body position and movement

Proprioceptors

monitor the position and movement of skeletal muscles and joints

vestibular sense

the sense of body movement and position, including the sense of balance

illusion

perception in which the way we perceive a stimulus doesn't match its physical reality

Gestalt

an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

figure-ground

A central principle of Gestalt psychology, involving the shifting of focus; as attention is focused on one object, all other features drop or recede into the background.

depth perception

the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

binocular cues

Information taken in by both eyes that aids in depth perception, including binocular convergence and retinal disparity.

convergence

A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object

retinal disparity

a binocular cue for perceiving depth by comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

monocular cues

depth cues, such as interposition and linear perspective, available to either eye alone

perceptual constancy

a tendency to experience a stable perception in the face of continually changing sensory input

shape constancy

the tendency to interpret the shape of an object as being constant, even when its shape changes on the retina

size constancy

An object is perceived as maintaining its size, regardless of the image projected on the retina.

color constancy

objects are perceived as maintaining their color, even with changing sensory data

perceptual set

a tendency to perceive or notice some aspects of the available sensory data and ignore others.

extrasensory perception (ESP)

the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition

parapsychology

the study of paranormal phenomena, including ESP and psychokinesis