Consciousness

Consciousness

our awareness of ourselves and our environment

Cognitive neuroscience

the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language)

Dual processing

the principle that information is often simultaneously processed on separate conscious and unconscious tracks.

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.

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, reversible 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

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. Dreams 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 (as distinct from its latent, or hidden, content)

Latent content

according to Freud, the underlying meaning of a dream (as distinct from its manifest content).

REM rebound

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

Hypnosis

a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur.

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.

Dissociation

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

Psychoactive drug

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

Stimulants

drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, and Ecstasy) that excite neural activity and speed up body functions

Amphetamines

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

Methamphetamine

a powerfully addictive drug that stimulates the central nervous system, with speeded-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 (“mindmanifesting”) 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).

THC

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

Near-death experience

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