Unit 1B 2025: Sleep, Sensation & Perception

Sensation

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

sensory receptors

sensory nerve endings that respond to stimuli

Perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

bottom-up processing

information processing that begins at the sensory receptors and works up to perception

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

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.

absolute threshold

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

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 (just noticeable difference)

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

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)

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

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

Cornea

the eye's clear, protective outer layer, covering the pupil and iris

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

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

Fovea

the central focal point in the retina, around which the eye's cones cluster

Young-Helmholtz Trichromatic (Three Color) Theory

the theory that the retina contains three different types of 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

parallel processing

the processing of many aspects of a problem or stimulus simultaneously

audition

the sense or act of hearing

Frequency

The number of complete waves that pass a given point in a certain amount of time

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

sensorineural hearing loss

the most common form of hearing loss, also called nerve deafness; caused by damage to the cochlea's receptor cells or to the auditory nerves

Conduction Hearing Loss

less common form of hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

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

volley theory

states that groups of neurons in the auditory system fire out of phase with each other to create a higher frequency of sound than a single neuron could produce. This is similar to how a group of archers can hit a target more frequently than an individual archer.

pain

an unpleasant sensory and emotional experience associated with actual or potential tissue damage

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.

phantom limb pain

pain in a limb (or extremity) that has been amputated

Gustation

the sensation of taste

Olfaction

our sense of smell

kinesthesis

the sense that provides information about the position and movement of individual body parts

vestibular sense

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

sensory interaction

the principle that one sense may influence another, as when the smell of food influences its taste

Ernst Weber

best known for "Weber's Law", the notion that the JND magnitude is proportional to the stimulus magnitude

consciousness

our awareness of ourselves and our environment

cognitive neuroscience

A field that attempts to understand the links between cognitive processes and brain activity.

dual processing

principle that info is often simultaneously processed on separate conscious and unconscious tracks

Blindsight

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

sequential processing

processing one aspect of a problem at a time; generally used to process new information or to solve difficult problems

sleep

periodic, natural loss of consciousness--as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

circadian rhythm

the biological clock; regular bodily rhythms 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 (EEG)

waves present on an EEG when we are awake but relaxing with our eyes closed.

Hallucinations

false sensory experiences, such as seeing something in the absence of an external visual stimulus

hypnagogic sensations

life-like hallucinations that occur shortly after falling asleep; usually sensation of falling or floating

suprachiasmatic nucleus (SCN)

a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness

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

sleep apnea treatment

CPAP machine (continuous positive airway pressure)

REM sleep behavior disorder

A sleep disturbance in which the mechanism responsible for paralyzing the body during REM sleep is not functioning, resulting in the acting out of dreams.

Dreams

occur most often during REM sleep; may be caused by activation-synthesis, or may be a way of cementing memories

Dream Theory: Information Processing Theory

dreams help us sort out the day's events and consolidate our memories

Dream Theory: Activation-Synthesis Theory

REM sleep triggers impulses that evoke random visual memories, which our sleeping brain weaves into stories

sound localization

we can locate sounds based on which ear they strike first

biopsychosocial of pain

Pain perception level would be influenced by neurotransmitters, learned associations, and the presence of others

Synesthesia

A perceptual experience in which stimulation of one sense produces additional unusual experiences in another sense

selective attention

the ability to focus on only one stimulus from among all sensory input

inattentional blindness

failure to detect stimuli that are in plain sight when our attention is focused elsewhere

change blindness

failing to notice changes in the environment; a form of inattentional blindness

perceptual set

a readiness to perceive a stimulus in a particular way

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness.

sleep stages

relaxed stage (alpha waves)

stage 1 (early sleep) (hallucinations)

stage 2 (sleep spindles - bursts of activity) (sleep talk)

stage 3 (delta waves) (sleepwalk/talk + wet the bed)

(REM) (sensory-rich dreams) (paradoxical sleep)

paradoxical sleep (REM)

Physiology is close to that of being awake bur the brainstem blocks all muscle movement. Active sleep. Brain wave patterns are similar to when awake - beta waves. Pulse and breathing quickens, body temp rises. Sleep paralysis

REM rebound

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

role that age plays in sleep

as you age you have shorter period of REM sleep than a youngster would

Delta waves (EEG)

the large, slow brain waves associated with deep sleep

somnambulism

the condition of walking or performing some other activity without awakening; also known as sleepwalking

Prosopagnosia

face blindness: a cognitive disorder of face perception in which the ability to recognize familiar faces, including one's own face (self-recognition), is impaired

fusiform face area

a region in the temporal lobe of the brain that helps us recognize the people we know

color blindness

a variety of disorders marked by inability to distinguish some or all colors

Nearsightedness/Farsightedness

-Nearsighted (close objects seen, far objects are blurry b/c focus point of light falls before the retina) -Farsighted (close objects blurry, far objects seen b/c focus point of light falls before the retina)

Afterimages

usually complementary in color to the original image, such as dark blue after a bright yellow stimulus.(opponent process theory)

Supertasters/Nontasters

There are both people who experience the sense of taste with far greater intensity than average, and those who cannot sense taste at all.

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement

cocktail party effect

the ability to focus on a particular stimulus, like a conversation, while filtering out other distracting sounds. For example, you might be able to hear your name in a noisy room. This phenomenon is a result of the brain's ability to selectively focus on certain stimuli while excluding others from conscious awareness

selective attention

the ability to focus on only one stimulus from among all sensory input

Depth Perception: binocular cues

retinal disparity and convergence

Depth Perception: Monocular Cues

relative clarity, relative size, texture gradient, interposition, linear perspective

Interposition

if one object partially blocks our view of another, we perceive it as closer

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance.

stroboscopic movement

a type of apparent movement based on the rapid succession of still images, as in motion pictures

phi phenemenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession (movie marquee, Christmas lights)

autokinetic effect

a small, stationary light in a darkened room will appear to move or drift because there are no surrounding cues to indicate that the light is not moving