A method for evaluating an animal’s capacity to recognize itself in which researchers determine whether the animal looking at itself in a mirror behaves in a manner indicating its recognition of a mark made on its body.

A sleep stage during which there is rapid eye movement, frequent dreams, and brain activity resembling that of waking periods.

The subjective conscious feeling that an amputated limb is still attached to one’s body.

A condition marked by high distractibility, low ability to concentrate, and impulsive behavior such as fast and frequent moving and talking.

Awareness and personal experience of oneself and one’s surroundings.

A conceptual problem that arises within dualistic theories (see dualism), namely, that there is no way to explain how a nonphysical mind can influence the physical body without violating laws of science.

Psychoactive drugs that increase nervous system activity and thus enhance alertness and energy.

Any chemical substance that affects the nervous system in a manner that alters conscious experience.

A depressant chemical compound found in beer, wine, and spirits that induces feelings of relaxation and a lessening of inhibitions.

Any medical condition that disrupts normal patterns of sleep.

The ability to project yourself backward or forward in time in your mind.

The sequence of changes in REM and non-REM sleep that everyone experiences in the same order.

A theory about the processes through which dreams are generated, claiming that dreams are the brain’s attempt to make sense of random brain signals.

A stimulant found in tobacco products that increases alertness while enhancing feelings of pleasure and emotional well-being.

Chemical substances whose primary psychoactive effect is the reduction of pain; can also induce feelings of euphoria and ecstasy.

Stimulants that strongly increase alertness and produce euphoric feelings.

Psychoactive drugs that reduce arousal in the central nervous system, lowering conscious experiences of excitability and anxiety.

An altered state of consciousness characterized by the subject’s unusual responsiveness to suggestions made by the hypnotist.

Any practice in which people focus their attention for an extended period of time, as a method for increasing their ability to concentrate.

A synthetic chemical that affects the firing of neurons in the brain, thereby inducing widespread biological, and thus psychological, effects.

The process of inducing a state of hypnosis in a subject, usually through procedures combining relaxation and focused attention.

A sleep disorder involving prolonged difficulty in falling asleep or staying asleep.

A disorder in which people suffer from brief pauses in breathing while they are asleep, causing them to wake up.

The proposition that the mind and body are two separate entities, with consciousness being a property of the nonphysical mind.

Compulsive, habitual, uncontrollable use of a harmful chemical substance.

The process of thinking about oneself, that is, thinking about one’s own experiences and how one appears to others.

Going without adequate sleep, which not only makes you tired but also impairs normal conscious experiences.

Substances that profoundly alter consciousness, causing people to experience phenomena such as hallucinations and a loss of contact with reality.

A problem in scientific explanation that arises if an organism’s capacity for consciousness is explained by proposing that a structure in its mind or brain is conscious. The problem is the failure to explain how consciousness arises in the mind or brain structure.

The approximately 24-hour cycle of changes in internal bodily processes.

Freud’s proposal that dreams help us stay asleep by depicting the fulfillment of unconscious wishes, thereby releasing pent-up mental energy.

A chemical compound found in coffee, tea, energy drinks, sodas, and chocolate that increases alertness.

A powerful stimulant that increases alertness and produces euphoric feelings, and thus is highly addictive.

A sleep disorder in which people experience sudden, extreme feelings of sleepiness during the day, even if they’ve had adequate sleep; sometimes accompanied by “microsleeps.”

A scientific facility for studying sleep; research participants spend nights sleeping while their biological rhythms and brain activity are monitored.

Psychoactive drugs prescribed for anxiety that reduce feelings of anxiety while also inducing muscular relaxation and sleepiness; may also produce pleasurable feelings.

Sleep stage in which brain activity differs from that of waking states, and breathing rate, heart rate, blood pressure, and body temperature are relatively low.

A drug that produces a wide range of effects that commonly include both euphoria and a relaxed, tranquil state.

A technique for recording and visually depicting electrical activity within the brain in which electrodes on the scalp record neural activity in underlying brain regions. The record of electrical activity through this method is called an electroencephalogram.

A recreational drug that can reduce anxiety and create feelings of intimacy and euphoria while raising body temperature; both a stimulant and a hallucinogen.