Psychology 1000 - Textbook Definitions (Chapters 5&6)

Absolute pitch

The ability to recognize or produce any note on a musical scale.

Absolute threshold

The minimal stimulus necessary for detection by an individual.

Activation-synthesis model

Theory that dreams result from the brain's attempts to synthesize or organize random internally generated signals and give them meaning.

Adaptive theory of sleep

Theory that organisms sleep for the purpose of self-preservation, to keep away from predators that are more active at night.

Addiction

Psychological or physical compulsion to take a drug, resulting from regular ingestion and leading to maladaptive patterns of behaviour and changes in physical response.

Ageusia

Inability to taste.

Alcoholism

Long-term pattern of alcohol addiction.

Anosmia

Inability to smell.

Basilar membrane

Structure in the cochlea where the hair cells are located.

Bottom-up processing

Perception that proceeds by transducing environmental stimuli into neural impulses that move into successively more complex brain regions.

Circadian rhythm

Pattern of sleep-wake cycles that in human beings roughly corresponds to periods of daylight and night.

Cochlea

Fluid-filled structure in the inner ear; contains the hair cells.

Cones

Photoreceptors responsive to colours.

Consciousness

Our immediate awareness of our internal and external states.

Convergence

Inward movement of the eyes to view objects close to oneself.

Deafness

Loss or lack of hearing.

Depressants

Class of drugs that slow the activity of the central nervous system.

Difference threshold or just noticeable difference

The minimal difference between two stimuli necessary for detection of a difference between the two.

Dissociation

A splitting of consciousness into two dimensions.

Endorphins

Chemicals that belong to a naturally occurring class of opiates that reduce pain in the nervous system.

Flashbacks

Recurrence of the sensory and emotional changes after the LSD has left the body.

Fovea

Centre of the retina, containing only cones, where vision is most clear.

Free nerve endings

Sensory receptors that convert physical stimuli into touch, pressure, or pain impulses.

Gate control theory of pain

Theory that certain patterns of neural activity can close a "gate" to keep pain information from travelling to parts of the brain where it is perceived.

Gustatory sense

Our sense of taste.

Hair cells

Sensory receptors that convert sound waves into neural impulses.

Hallucinogens

Substances that dramatically change one's state of awareness, causing powerful changes in sensory perception.

Hypnagogic state

A pre-sleep period often characterized by vivid sensory phenomena.

Hypnosis

A seemingly altered state of consciousness during which individuals can be directed to act or experience the world in unusual ways.

Information-processing theory

Hypothesis that dreams are the mind's attempt to sort out and organize the day's experiences and to fix them in memory.

Insomnia

Sleep disorder characterized by a regular inability to fall asleep or stay asleep.

Lucid dreams

Dreams in which sleepers fully recognize that they are dreaming, and occasionally actively guide the outcome of the dream.

Meditation

Technique designed to turn one's consciousness away from the outer world toward one's inner cues and awareness.

Meissner's corpuscles

Sensory receptors that convert physical stimuli about sensory touch on the fingertips, lips, and palms.

Merkel's discs

Sensory receptors that convert information about light to moderate pressure on the skin.

Monocular cues

Visual clues about depth and distance that can be perceived using information from only one eye.

Narcolepsy

Sleep disorder marked by uncontrollable urge to fall asleep.

Non-REM sleep (NREM)

Stages 1 through 4 of normal sleep pattern.

Odorants

Airborne chemicals that are detected as odours.

Olfactory bulb

The first region where olfactory information reaches the brain on its way from the nose.

Olfactory receptor neurons

Sensory receptor cells that convert chemical signals from odorants into neural impulses that travel to the brain.

Olfactory sense

Our sense of smell.

Opioids

Class of drugs derived from the sap of the opium poppy.

Optic nerve

The bundle of axons of ganglion cells that carries visual information from the eye to the brain.

Ossicles

Tiny bones in the ear called the maleus (Hammer), incus (Anvil), and stapes (Stirrup).

Oval window

A membrane separating the ossicles and the inner ear, deflection of which causes a wave to form in the cochlea.

Pacinian corpuscles

Sensory receptors that respond to vibrations and heavy pressure.

Papillae

Bumps on the tongue that contain clumps of taste buds.

Perception

The conscious recognition and identification of a sensory stimulus.

Perceptual constancies

Our top-down tendency to view objects as unchanging, despite shifts in the environmental stimuli we receive.

Perceptual set

Readiness to interpret a certain stimulus in a certain way.

Photoreceptors

The sensory receptor cells for vision, located in the retina.

Preconsciousness

Level of awareness in which information can become readily available to consciousness if necessary.

Psychoactive drugs

Chemicals that affect awareness, behaviour, sensation, perception, or mood.

Rapid eye movement sleep (REM)

Stage of sleep associated with rapid and jagged brainwave patterns, increased heart rate, rapid and irregular breathing, rapid eye movements, and dreaming.

Restorative theory of sleep

Theory that we sleep to allow the brain and body to restore certain depleted chemical resources and eliminate chemical wastes that have accumulated during the waking day.

Retina

A specialized sheet of nerve cells in the back of the eye containing the sensory receptors for vision.

Retinal disparity

The slight difference in images processed by the retinas of each eye.

Reward learning pathway

Brain circuitry that is important for learning about rewarding stimuli.

Reward-deficiency syndrome

Theory that people might abuse drugs because their reward centre is not readily activated by usual life events.

Rods

Photoreceptors most responsive to levels of light and dark.

Ruffini's end-organs

Sensory receptors that respond to heavy pressure and joint movement.

Sedative-hypnotic drugs

Class of drugs that produces feelings of relaxation and drowsiness.

Sensation

The act of using our sensory systems to detect environmental stimuli.

Sensory adaptation

The process whereby repeated stimulation of a sensory cell leads to a reduced response.

Sensory receptor cells

Specialized cells that convert a specific form of environmental stimuli into neural impulses.

Sensory transduction

The process of converting a specific form of environmental stimuli into neural impulses.

Sleep apnea

Sleep disorder characterized by repeatedly ceasing to breathe during the night, depriving the brain of oxygen and leading to frequent awakenings.

Sleep spindles

Bursts of brain activity lasting a second or two; occur during Stage 2 sleep.

Sound waves

Vibrations of the air in the frequency of hearing.

Stimulants

Substances that increase the activity of the central nervous system.

Suprachiasmatic nucleus (SCN)

A small group of neurons in the hypothalamus responsible for coordinating the many rhythms of the body.

Taste buds

Clusters of sensory receptor cells that convert chemical signals from food into neural impulses that travel to the brain.

Tolerance

Mark of physical dependence on a drug, in which the person is required to take incrementally larger doses of the drug to achieve the same effect.

Tonotopic map

Representation in the auditory cortex of different sound frequencies.

Top-down processing

Perception processes led by cognitive processes, such as memory or expectations.

Transduction

Process that involves converting stimulus energy into neural impulses that can be interpreted by the brain.

Tympanic membrane

The ear drum.

Unconscious state

State in which information is not easily accessible to conscious awareness.

Withdrawal symptoms

Unpleasant and sometimes dangerous side effects of reducing intake of a drug after a person has become addicted.