Knowt
unit 1 v2
consciousness: our subjective awareness of ourselves and our environment.
cognitive neuroscience: the interdisciplinary study of the brain activity linked with cognition (thinking, knowing, remembering, and communicating).
dual processing: the principle that information is often simultaneously processed on separate conscious and unconscious tracks.
blindsight: a condition in which a person can respond to a visual stimulus without consciously experiencing it.
parallel processing: processing multiple aspects of a stimulus or problem simultaneously.
sequential processing: processing one aspect of a stimulus or problem at a time; generally used to process new information or to solve difficult problems.
sleep: a periodic, natural loss of consciousness — as distinct from unconscious- ness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)
circadian rhythm: our biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.
REM sleep: rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active. (Sometimes called R sleep.)
alpha waves: the relatively slow brain waves of a relaxed, awake state.
NREM sleep: non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep.
hallucinations: false sensory experiences, such as seeing something in the absence of an external visual stimulus.
hypnagogic sensations: bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning to sleep. (Also called hypnic sensations.)
delta waves: the large, slow brain waves associated with deep sleep.
suprachiasmatic nucleus (SCN): a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN adjusts melatonin production, thus modifying our feelings of sleepiness.
insomnia: recurring problems in falling or staying asleep.
narcolepsy: a sleep disorder characterized by uncontrollable sleep attacks. The affected person may lapse directly into REM sleep, often at inopportune times.
sleep apnea: a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.
REM sleep behavior disorder: a sleep disorder in which normal REM paraly- sis does not occur; instead, twitching, talking, or even kicking or punching may occur, often acting out one’s dream.
dream: a sequence of images, emotions, and thoughts passing through a sleeping person’s mind.
REM rebound: the tendency for REM sleep to increase following REM sleep deprivation.
sensation: 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 pre- disposing 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 (three-color) 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.
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 [KOHK-lee-uh]: 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.
