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 beings 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 the environment
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 theory
a theory predicting how and when we detect the presence of a faint stimulus amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and alertn
priming
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
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
weber's law
the principle that, to be perceived as different, two stimuli must differ by constant percentage (rather than a constant amount)
sensory adaptation
diminished sensitivity as a consequence of constant stimulation
prospagnosia
face blindness
transduction
conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, 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; what we know as the color names blue, green and so forth
intensity
the amount of energy in a light or sound wave, which as 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 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
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 response
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 eyes 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
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 the specific features of the stimulus, such as shape, angle or movement
parallel processing
the processing of many aspects of a problem simultaneously; the brains 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 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, 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
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
sensorineural hearing loss
hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness
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 f body movement and position, including the sense of balance
gate-control theory
the theory that the spinal cord contains a neurological "gate" that blocks pain signals or allow 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
sensory interaction
the principle that one sense may influence another, as when the smell of food influences its taste
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 organized 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 toe judge distance
visual cliff
a laboratory device for testing depth perception in infants and young animals
binocular cues
depth cues, such as retinal disparity, that depend 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 objects
monocular cues
depth cues, such as 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
perceptual constancy
perceiving objects as unchanging (having consistent shapes, size, lightness, and color) even 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
the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition