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 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% of the time
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.) (Myers Psychology 8e p. 201)
Weber's Law
Principle that, to be percieved 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
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
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
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. (Myers Psychology 8e p. 206)
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 several 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 color
opponent-process theory
the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision
color constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
visual capture
the tendency for vision to dominate the other senses, as when we perceive voices in films as coming from the screen we see rather than from the projector behind us
audition
the sense of hearing
frequency
the number of complete wavelengths that pass a point in a given time (for example, per second)
pitch
a tone's 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
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
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
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
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
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
gestalt
an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes
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 display
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
convergence
a binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object
perceptual constancy
perceiving objects as unchanging (having consistent lightness, color, shape, and size) even as illumination and retinal images change
perceptual adaption
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. Said to include telepathy, clairvoyance, and precognition
parapsychology
the study of paranormal phenomena, including ESP and psychokinesis.