Studied by 22 peopleSensation
the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
Sensory receptors
sensory nerve endings that respond to stimuli.
Perception
the process by which our brain organizes and interprets sensory information, enabling us to recognize objects and events as meaningful.
Bottom-up processing
information processing 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.
Transduction
conversion of one form of energy into another. In sensation, the transforming of physical energy, such as sights, sounds, and smells, into neural impulses the brain can interpret.
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 stimulus energy 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 (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
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 (jnd).
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.
Wavelength
the distance from the peak of one light wave or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short gamma waves 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 wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the wave’s amplitude (height).
Cornea
the eye’s clear, protective outer layer, covering the pupil and iris.
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 back 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 images of near or far objects on the retina.
Rods
retinal receptors that detect black, white, and gray, and are sensitive to movement. Rods are necessary for peripheral and twilight vision, when cones don’t respond.
Cones
retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and give rise to color sensations.
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.
Fovea
the central focal point in the retina, around which the eye’s cones cluster.
Young-Helmholtz trichromatic theory
the theory that the retina contains three different types of 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
the theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.
Feature detectors
nerve cells in the brain’s visual cortex that respond to specific features of the stimulus, such as shape, angle, or movement.
Parallel processing
processing multiple aspects of a stimulus or problem simultaneously.
Audition
the sense or act of hearing.
Frequency
the number of complete wavelengths that pass a point in a given time (for example, per second).
Pitch
a tone’s experienced highness or lowness; depends on frequency.
Middle ear
the chamber between the eardrum and the cochlea containing three tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window.
Cochlea
a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses.
Inner ear
the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
Sensorineural hearing loss
the most common form of hearing loss, caused by damage to the cochlea’s receptor cells or to the auditory nerve; also called nerve deafness.
Conduction hearing loss
a less common form of hearing loss, caused by damage to the mechanical system that conducts sound waves to the cochlea.
Cochlear implant
a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
Place theory
in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated. (Also called place coding.)
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. (Also called temporal coding.)
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 or by information coming from the brain.
Gustation
our sense of taste.
Olfaction
our sense of smell.
Kinesthesis
our movement sense; our system for sensing the position and movement of individual body parts.
Vestibular sense
our balance sense; our sense of body movement and position that enables our sense of balance.
Sensory interaction
the principle that one sense can influence another, as when the smell of food influences its taste.
Embodied cognition
the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments.
Selective attention
focusing 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; a form of inattentional blindness.
Perceptual set
a mental predisposition to perceive one thing and not another.
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 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.
Binocular cue
a depth cue, such as retinal disparity, that depends on the use of two eyes.
Convergence
a cue to nearby objects’ distance, enabled by the brain combining retinal images.
Retinal disparity
a binocular cue for perceiving depth. By comparing retinal images from the two eyes, the brain computes distance — the greater the disparity (difference) between the two images, the closer the object.
Monocular cue
a depth cue, such as interposition or linear perspective, available to either eye alone.
Stroboscopic movement
an illusion of continuous movement (as in a motion picture) experienced when viewing a rapid series of slightly varying still images.
Phi phenomenon
an illusion of movement created when two or more adjacent lights blink on and off in quick succession.
Autokinetic effect
the illusory movement of a still spot of light in a dark room.
Perceptual constancy
perceiving objects as unchanging (having consistent color, brightness, shape, and size) 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.
Perceptual adaptation
the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field.
Cognition
all the mental activities associated with thinking, knowing, remembering, and communicating.
Metacognition
cognition about our cognition; keeping track of and evaluating our mental processes.
Concept
a mental grouping of similar objects, events, ideas, or people.
Prototype
a mental image or best example of a category. Matching new items to a prototype provides a quick and easy method for sorting items into categories (as when comparing feathered creatures to a prototypical bird, such as a crow).
Schema
a concept or framework that organizes and interprets information.
Assimilation
interpreting our new experiences in terms of our existing schemas.
Accommodation
in developmental psychology, adapting our current schemas (understandings) to incorporate new information.
Creativity
the ability to produce new and valuable ideas.
Convergent thinking
narrowing the available problem solutions to determine the single best solution.
Divergent thinking
expanding the number of possible problem solutions; creative thinking that diverges in different directions.
Executive functions
cognitive skills that work together, enabling us to generate, organize, plan, and implement goal-directed behavior.
Algorithm
a methodical, logical rule or procedure that guarantees solving a particular problem. Contrasts with the usually speedier — but also more error-prone — use of heuristics.
Heuristic
a simple thinking strategy—a mental shortcut — that often allows us to make judgments and solve problems efficiently; usually speedier but also more error-prone than an algorithm.
Insight
a sudden realization of a problem’s solution; contrasts with strategy-based solutions.
Confirmation bias
a tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence.
Fixation
in cognition, the inability to see a problem from a new perspective; an obstacle to problem solving.
Mental set
a tendency to approach a problem in one particular way, often a way that has been successful in the past.
Intuition
an effortless, immediate, automatic feeling or thought, as contrasted with explicit, conscious reasoning.
Representative heuristic
judging the likelihood of events in terms of how well they seem to represent, or match, particular prototypes; may lead us to ignore other relevant information.
Availability heuristic
judging the likelihood of events based on their availability in memory; if instances come readily to mind (perhaps because of their vividness), we presume such events are common.
Overconfidence
the tendency to be more confident than correct — to overestimate the accuracy of our beliefs and judgments.
Belief perseverance
the persistence of one’s initial conceptions even after the basis on which they were formed has been discredited.
Framing
the way an issue is posed; how an issue is framed can significantly affect decisions and judgments.
Nudge
framing choices in a way that encourages people to make beneficial decisions.
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