selective attention
the focusing of conscious awareness on a particular stimulus, as in the cocktail party effect
inattentional blindness
failing to see visible objects when our attention is directed elsewhere
visual capture
the tendency for vision to dominate the other senses
gestalt
an organized whole. psychologists emphasized our tendency to integrate pieces of information into meaningful wholes
figure-ground
the organization of the visual field into objects that stand out from their surroundings
grouping
the perceptual tendency to organize stimuli into coherent schemas
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
retinal disparity
a binocular cue for perceiving depth: By comparing images from the two eyeballs, the brain computes distance - the greater the difference between the two images, the closer the object
convergence
a binocular cue for perceiving depth; the extent to which the eyes go inward when looking at an object. The greater the inward strain, 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 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
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
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
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
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 dtect the presence of a faint stimulus amid background stimulation. Assumes there is no single absolute threshold and detection depends partly on a person's experience, expectations, motivation, and level of fatigue
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 _____ as a just noticeable difference
Weber's law
the principle that, to be perceived 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
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; 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
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
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
acuity
the sharpness of vision
nearsightedness
a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina
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
rods
retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision.
cones
retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions.
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 blank space 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 specific features of the stimulus, such as shape, angle, or movement
olfaction
the sense of smell