AP Psychology- Unit 3- Sensation & Perception

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

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

Top-down processing

information processing guided by higher-level mental process, as when we construct perceptions drawing out our experience and expectation.

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 stimuli ("signal") amid background stimulation ("noise"). Assume that there is no single absolute threshold and that focuses more on the processing of briefly stored information. (e.g. what determines a "hit", "miss," "false alarm" or "correct rejection")

Difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (also called just noticeable difference or JND.)

Subliminal Sensation

detection of stimuli below absolute threshold

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).

Sensory Adaptation

diminished sensitivity as a consequence of constant stimulation.

Transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies into neural impulses.

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 determine by the wavelength of light; what we know as the color names blue, green, and so forth.

Pupil

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

Iris

a ring of muscle tissue that forms the color portions of the eye around the pupil and controls the size of the pupil opening.

Lens

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

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.

Acuity

the sharpness of vision.

Nearsightedness

a condition in which nearby objects are seen more clearly than distant objects because distant objects focus right in front of the retina.

Farsightedness

the condition in which faraway objects are seen more clearly that near objects because the image of near objects is focused behind the retina.

Rods

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

Cones

receptors cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine details and give rise to color sensation.

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; no receptors cells are located there. Creates a gap in our vision that is "filled" by the brain.

Fovea

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

Feature detectors

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

Parallel processing

the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrast with the step-by-step (serial) processing of most computers and of conscious problem solving.

Young-Helmholtz Trichromatic theory

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

Opponent-Process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision; useful for explaining the phenomenon of "after-images"

Color constancy

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

Audition

the sense of hearing

Frequency

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

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.

Inner ear

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

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.

Gate-Control theory

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

Kinesthesis

the system for sensing the position and movement of individual body parts; enabled by feedback from proprioceptors (which provide info about the movement of muscles, tendons, joints)

Vestibular sense

the sense of body movement and position, including the sense of balance; enabled by feedback from semicircular canals in inner ear

basilar membrane

area within the cochlea where hair cells are located

gestalt

a perceptual whole; derived from German word meaning "form" or "whole"

selective attention

ability to attend to only a limited amount of sensory information at one time

figure-ground

A gestalt perceptual phenomenon; the organization of the visual field into objects that stand out from their surroundings

grouping

the perceptual tendency to organize stimuli into coherent groups

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

laboratory device for testing depth perception among infants and young animals; its use demonstrated that, among most species, animals have the ability to perceive depth by the time they are mobile

binocular cues

depth cues that require the combined input of both eyes

monocular cues

depth cues that only require input from one eye; often used in 2D art to create illusion of depth

convergence

a binocular cue for perceiving depth; the more the eyes strain to turn inwards to view an object, the closer the object is (note: only a factor at close ranges)

interposition

monocular cue for depth perception; if one object partially blocks our view of another object, we perceive it as closer

relative motion

monocular cue for depth perception; as we move, stationary objects seem to "move" as well. Objects above a fixation point move "with" us, objects below the fixation point move "past" us.

phi phenomenon

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

stroboscopic movement

the brain's perception of continuous movement in a rapid series of slightly varying images; this is how we perceive motion in film and animation

perceptual constancy

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

perceptual adaptation

the ability to adjust to an altered perceptual reality; in vision, the ability to adjust to an artificially displaced or inverted visual field (as when wearing visual displacement goggles).

perceptual set

mental predisposition to perceive one thing and not another (for example, due to suggestion or expectations based on prior learning)

human factors psychology

Branch of psychology that explores how people & machines interact and how physical environment can be adapted to human behaviors

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

visual capture

the phenomenon that occurs when vision overtakes some other, conflicting sensory input

retinal disparity

a binocular cue for perceiving depth; by comparing images from the two eyeballs, the brain computes distance - the greater the disparity (difference) between the two images, the close the object

Inattentional Blindness

failing to see visible objects when our attention is directed elsewhere

cochlear implant

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

Sensorineural Hearing Loss

hearing loss due to failure of the auditory nerve

Conduction Hearing Loss

hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

Decibels

measure of loudness of sound

Pitch

the property of sound that varies with variation in the frequency of vibration

Intensity

the magnitude of sound (usually in a specified direction)

Priming

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

Psychophysics

the branch of psychology concerned with quantitative relations between physical stimuli and their psychological effects