Sensation and Perception

transduction

Conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells into neural impulses our brains can interpret

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

sensory receptors

sensory nerve endings that respond to stimuli

selective attention

the focusing of conscious awareness on a particular stimulus

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment, a form of inattentional blindness

Psychphysics

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

absolute threshold

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

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.

subliminal

below one's absolute threshold for conscious awareness

difference threshold

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

Priming

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

Weber's Law

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

perceptual set

a mental predisposition to perceive one thing and not another

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

Wavelength

the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission

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

Intensity

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude (height)

sensory adaptation

Diminished sensitivity as a consequence of constant stimulation;

cocktail-party phenomenon

a phenomenon in which people tune in one message even while they filter out others nearby

cornea

The eye's clear, protective outer layer, covering the pupil and the iris

pupil

The adjustable opening in the center of the eye through which light enters

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.

lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

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.

energy senses

The sense of vision, hearing and touch; they gather energy in the form of light, sound waves, and pressure.

chemical senses

Taste and smell (chemoreceptors)

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.

accommodation

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

feature detector

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

optic nerve

Nerve that carries neural impulses from the eye to the brain.

occipital lobe

Portion of the cerebral cortex lying at the back of the head; visual areas

visible light

That portion of the electromagnetic spectrum that can be detected as various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm. (nanometers)

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. These detect fine detail and give rise to color sensations.

fovea

The central focal point in the retina, around which the eye's cones cluster

Young-Helmholtz trichromatic theory

the theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color. AKA three-color theory

feature detectors

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

parellel processing

The processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision.

gestalt

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

figure-ground

the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

grouping

the perceptual tendency to organize stimuli into coherent groups

blind spot

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

trichromatic theory

Idea that color vision is based on our sensitivity to three different colors: blue, green, and red ; does not explain afterimages and color blindness.

color blindness

A sex-linked trait in which an individual cannot perceive certain colors.

afterimages

The visual impression that remains after the original image has been 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.

vision

Sense of sight;

detects light energy (photons).

hearing

The vibration of sound waves on the eardrums and the firing of electrochemical impulses in the brain.

sound waves

Successive pressure variations in the air that vary in amplitude and frequency.

amplitude

The height of the sound wave and determines loudness, which is measured in decibels.

frequency

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

audition

the sense or act of hearing

pitch

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

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

cochlea

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

pitch theories

- Theories explaining how we hear different pitches or tones. Explains that the hair cell sin the cochlea respond to different frequencies of sound bases o where they are located in the cochlea.

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

sensoryneural hearing loss

hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness

conduction hearing loss

a less common form of hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

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. (Also called temporal theory.)

place theory

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

conduction deafness

Hearing loss due to problems with the bones of the middle ear.

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

visual cliff

a laboratory device for testing depth perception in infants and young animals

binocular cue

a depth cue, such as retinal disparity, that depends on the use of two eyes

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 cue

a depth cue, such as interposition or linear perspective, available to either eye alone

phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession

perceptual constancy

perceiving objects as unchanging (having consistent lightness, color, shape, and size) even as illumination and retinal images change

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

perceptual adaptation

the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

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.

Olfaction

sense of smell

kinesthesis

our movement sense - our system for sensing the position and movement of individual body parts

vestibular sense

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

sensory interaction

the principle that one sense may influence another, as when the smell of food influences its taste

embodied cognition

the influence of bodily sensations, gestures, and other states on cognitive preferences and judgements