s unit vocab ap psychology 2025

consciousness

our subjective awareness of ourselves and our environment

circadian rhythm

our biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle

paradoxical 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.

REM rebound

the tendency for REM sleep to increase following REM sleep deprivation.

REM sleep behavior disorder

a sleep disorder in which normal REM paralysis does not occur; instead, twitching, talking, or even kicking or punching may occur, often acting out one’s dream

activation-synthesis theory

dreams are the brain’s attempt to synthesize random neural activity.

consolidation theory

sleep consolidates our memories by replaying recent learning and strengthening neural connections

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.

somnambulism

sleepwalking; a sleep disorder characterized by persistent incidents of complex motor activity during slow-wave NREM sleep

hypnagogic sensations

bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning to sleep.

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

absolute threshold

the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time

just-noticeable difference

the minimum difference between two stimuli required for detection 50 percent of the time

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

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)

synesthesia

the brain circuits for two or more senses become joined in a phenomenon in which the stimulation of one sense triggers an experience of another

accomodation

in sensation and perception, the process by which the eye’s lens changes shape to focus images of near or far objects on the retina

trichromatic theory

one of several concepts of the physiological basis of color vision, as derived from experiments on color mixture in which all hues were able to be matched by a mixture of three primary colors

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.

photoreceptor

a visual receptor: a retinal rod or a retinal cone

prosopagnosia

face-blindness; a form of visual agnosia in which the ability to perceive and recognize faces is impaired, whereas the ability to recognize other objects may be relatively unaffected

blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it

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.)

volley theory

the principle that individual fibers in an auditory nerve respond to one or another stimulus in a rapid succession of rhythmic sound stimuli, whereas other fibers in the nerve respond to the second, third, or nth stimulus.

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.)

pheromone

olfactory chemical messages; a chemical signal that is released outside the body by members of a species and that influences the behavior of other members of the same species.

gate control theory

the hypothesis that the subjective experience of pain is modulated by large nerve fibers in the spinal cord that act as gates, such that pain is not the product of a simple transmission of stimulation from the skin or some internal organ to the brain. rather, sensations from noxious stimulation impinging on pain receptors have to pass through these spinal gates to the brain in order to emerge as pain perceptions.

phantom limb sensation

the feeling that an amputated limb is still present, often manifested as a tingling or, occasionally, painful sensation in the area of the missing limb (phantom limb pain)

vestibular sense

our balance sense; our sense of body movement and position that enables our sense of balance.

kinesthesis

our movement sense; our system for sensing the position and movement of individual body parts