Psych Unit 4 and 5

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. We experience the difference threshold as a just noticeable difference (jnd).

Weber’s law

the principle that, to be perceived as different, two stimuli must differ by a constant percentage (rather than a constant amount).

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.

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

Optic nerve

the nerve that carries neural impulses from the eye to the brain.

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 (for example, per second).

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.

Sensorineural 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.

Figure-ground

the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Grouping

the perceptual tendency to organize stimuli into coherent groups.

Depth perception

the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance.

Visual cliff

a laboratory device for testing depth perception in infants and young animals.

Binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes.

Retinal disparity

a binocular cue for perceiving depth: By comparing images from the retinas in the two eyes, the brain computes distance-the greater the disparity (difference) between the two images, the closer the object.

Monocular cues

depth cues, such as interposition and linear perspective, available to either eye alone.

Phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession.

Perceptual constancy

perceiving objects as unchanging (having consistent shapes, size, lightness, and color) even as illumination and retinal images change.

Color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.

Perceptual adaptation

in vision, the ability to adjust to an artificially displaced or even inverted visual field.

Perceptual set

a mental predisposition to perceive one thing and not another.

Extrasensory perception (ESP)

the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition.

Parapsychology

the study of paranormal phenomena, including ESP and psychokinesis.

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.

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.

Insomnia

Recurring problems in falling or staying asleep.

Dream

a sequence of images, emo-tions, 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 ("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.