Unit 1b - Sensation

consciousness

our awareness of ourselves and our environment

circadian rhythm

the 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.

alpha waves

the relatively slow brain waves of a relaxed, awake state

sleep

periodic, natural loss of consciousness--as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

Hallucinations

false sensory experiences, such as seeing something in the absence of an external visual stimulus

delta waves

the large, slow brain waves associated with deep sleep

NREM sleep

non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep

insomnia

recurring problems in falling or staying asleep

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks. The sufferer 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

night terrors

a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during Stage 4 sleep, within two or three hours of falling asleep, and are seldom remembered

dream

a sequence of images, emotions, and thoughts passing through a sleeping person's mind.

These are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the dreamer's delusional acceptance of the content and later difficulties remembering it.

manifest content

according to Freud, the remembered story line of a dream

latent content

according to Freud, the underlying meaning of a dream

REM rebound

the tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep)

posthypnotic suggestion

a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviors

Hypnosis

a social interaction in which one person suggests to another that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur

Dissociation

a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others

psychoactive drugs

a chemical substance that alters perceptions and moods

Tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug's effect

withdrawal

the discomfort and distress that follow discontinuing the use of an addictive drug

physical dependence

a physiological need for a drug, marked by unpleasant withdrawal symptoms when the drug is discontinued

psychological dependence

a psychological need to use a drug, such as to relieve negative emotions

addiction

compulsive drug craving and use, despite adverse consequences

Depressants

drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions

Barbiturates

drugs that depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment

Opiates

opium and its derivatives, such as morphine and heroin; they depress neural activity, temporarily lessening pain and anxiety

Amphetamines

drugs that stimulate neural activity, causing sped-up body functions and associated energy and mood changes

Methamphetamine

a powerfully addictive drug that stimulates the central nervous system, with sped-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels

Ecstasy (MDMA)

a synthetic stimulant and mild hallucinogen. Produces euphoria and social intimacy, but with short-term health risks and longer-term harm to serotonin-producing neurons and to mood and cognition.

Hallucinogens

psychedelic ("mind-manifesting") drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input

LSD

a powerful hallucinogenic drug; also known as acid (lysergic acid diethylamide)

near-death experience

an altered state of consciousness reported after a close brush with death (such as through cardiac arrest); often similar to drug-induced hallucinations

THC

the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations

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

selective attention

the focusing of 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

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 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

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)

instead of constant differences, they are relative

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

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

accommodation

the 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

more sensitive

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. These 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

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 many 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 (three-color) 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 any color.

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, 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

audition

the sense or act of hearing

Frequency

the number of complete wavelengths that pass a point in a given time

pitch

a tone's experienced 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

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

place theory

in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated

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

conduction hearing loss

hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

sesorineural hearing loss

hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

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

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.

sensory interaction

the principle that one sense may influence another, as when the smell of food influences its taste

gestalt

an organized whole.

These psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.