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 highler-level mental processes, as when we construct perceptions drawing on our experience and expectations.
Psychophysics
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
predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) Assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectation, motivation, and lev
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. We experience the difference threshold as a just noticeable difference. (Also called just noticeable difference or jnd.)
Weber's Law
to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)
Priming
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
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
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
Fovea
the central focal point in the retina, around which the eye's cones cluster
Farsightedness
a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina
Parallel Processing
the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision
Young-Helmholtz Theory
The theory that the retina contains three different color receptors--one most sensitive to red, one to greeen, one to blue--which combined can produce the perception of any color.
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.
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
nerve responsible for carrying impulses for the sense of sight from the retina 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
Nearsightedness
a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of 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
Opponent-process Theory
the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision.
Acuity
sharpness of vision
Feature Detectors
nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement
Audition
the sense of hearing
Frequency
the number of complete wavelengths that pass a point in a given time (for example, per second)
Pitch
how high or low a sound is
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
Conduction Hearing Loss
hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea
Sensorineural Hearing Loss
hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness
Gate-Control Theory
Melzack and Wall's theory that the spinal cord contains a neurological "gate" that blocks or allows pain signals to pass on to the brain.
Sensory Interaction
the principle that one sense may influence another, as when the smell of food influences its taste
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
Cochlear Implant
a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea
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).
Color Constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
Human Factors Psychology
a branch of psychology that explores how people and machines interact and how machines and physical environments can be made safe and easy to use
Relative Size
a monocular cue for perceiving depth; the smaller retinal image is farther away
Convergence
a binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object
Relative Brightness
a monocular cue, objects up close appear brighter than objects farther away
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, such as retinal disparity and convergence, that depend on the use of two eyes
Monocular Cues
depth cues, such as interposition and linear perspective, available to either eye alone
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
Interposition
monocular visual cue in which two objects are in the same line of vision and one patially conceals the other, indicating that the first object concealed is further away
Relative Clarity
a monocular cue for perceiving depth; hazy objects are farther away than sharp, clear objects
Texture Gradient
a monocular cue for perceiving depth; a gradual change from a coarse distinct texture to a fine, indistinct texture signals increasing distance. objects far away appear smaller and more densely packed
Relative Height
a monocular cue for perceiving depth; objects higher in our field of vision are perceived as farther away
Relative Motion
Monocular distance cue based on the fact that moving objects appear to move a greater distance when they are close to the viewer than when they are far away
Linear Perspective
a monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance
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
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
the controversial claim that perception can occur apart from sensory input. Said to include telepathy, clairvoyance, and precognition.
Parapsychology
the study of paranormal phenomena, including ESP and psychokinesis