Studied by 24 people
sensation
process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
perception
process of organizing and interpreting sensory information, to recognize meaningful objects and events
bottom-up processing
analysis that begins with sensory receptors and works up to brain’s integration of sensory information (new info!)
top-down processing
information processing where we construct perceptions drawing on experience and expectations (things we alr know)
selective attention
conscious awareness of particular stimulus
inattentional blindness
failing to see visible objects when our attention is directed elsewhere
change blindness
failing to notice changes in the environment
transduction
conversion of one form of energy into another - in sensation, transforming of stimulus energies like sights, sounds, and smells, into neural impulses brain can interpret
psychophysics
study of relationships between physical characteristics of stimuli, like their intensity, and our psychological experience of them
absolute threshold
minimum stimulation needed to detect a particular stimulus 50% of the time
signal detection theory
theory predicting how and when we detect the presence of 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
priming
unconscious activation of certain associations, thus predisposing one’s perception, memory, or response
difference threshold
minimum difference between two stimuli required for detection 50% of the time - “just noticeable difference” (jnd)
weber’s law
principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage rather than constant amount
sensory adaptation
diminished sensitivity as a consequence of constant stimulation
perceptual set
mental predisposition to perceive one thing and not another
wavelength
distance from peak of one light or sound wave to peak of the next - electromagnetic wavelengths vary from short blips of cosmic rays to long pulses of radio transmission
hue
dimension of color that is determined by wavelength of light; what we know as color names like blue, green, red
intensity
amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by wave’s amplitude
pupil
adjustable opening in center of the eye through which light enters
iris
ring of muscle tissue, forms colored portion of the eye around pupil and controls size of pupil opening
lens
transparent structure behind the pupil that changes shape to help focus images on the retina
retina
light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual info
accomodation
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 concentrated near the center of the retina that function in daylight or in well-lit conditions - cones detect fine detail and give rise to color sensations
optic nerve
nerve that carries neural impulses from eye to brain
blind spot
point where optic nerve leaves eye, creating a “blind” spot because no receptor cells are located there
fovea
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 stimulus, such as shape, angle, or movement
parallel processing
processing of many aspects of a problem simultaneously; brain’s natural mode of information processing for many functions, including vision - contrasts with step-by-step (serial) processing of most computers and of conscious problem solving
Young-Helmholtz trichromatic (three-color) theory
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
theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision - example: some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green
gestalt
an organized whole - Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes
figure-ground
organization of the visual field into objects (figures) that stand out from their surroundings (ground)
grouping
perceptual tendency to organize stimuli into coherent groups (proximity, continuity, closure)
depth perception
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, 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 object
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, brightness, 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 (checkerboard colors)
perceptual adaptation
in vision - the ability to adjust to an artificially displaced or inverted visual field
Note
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