Sensation and Perception - Unit 4 (AP Psychology)

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 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

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 one’s environment.

Absolute Threshold

The minimum stimulation needed to detect a particular stimulus 50% 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% of the time; we experience the difference threshold as a just noticeable difference

Weber’s Law

The principle that, to be perceived as different, two stimuli must differ by a constant 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, such as sights, sounds, and smells, into neural impulses our brains can interpret

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.

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.

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

Lens

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

Accomodation

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

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.

Feature Detectors

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

Parallel Processing

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

Opponent-Process Theory

The theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision.

Audition

The sense or act of hearing

Frequency

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

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 cochleas oval window.

Cochlea

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

Inner Ear

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

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

Conduction Hearing Loss

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. Can be caused by fluids, foreign objects, a ruptured eardrum or head trauma.

Sensorineural Hearing Loss

Also called Nerve Deafness; hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves. Can be caused by aging or noise damage (headphones).

Cochlear Implant

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

Kinesthesis

The 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

Gate-Control Theory

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

Sensory Interaction

The principle that one sense may influence another (a stimulus creates a response)

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)

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 Cues

Depth cues (i.e. retinal disparity) that depend on the use of two eyes

Monocular Cues

Depth cues (i.e. interposition and 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; often used by filmmakers

Perceptual Constancy

Perceiving objects as unchanging (having consistent shapes, size, lightness, and color) 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

In vision, the ability to adjust to an artificially displaced or even inverted visual field

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 phenomenon, including ESP and psychokinesis.