Understanding Consciousness, Sleep, and Sensation

Consciousness

our awareness of ourselves and our environment.

Preconscious

something that is not in our conscious, but can be easily pulled into consciousness, such as memories.

Unconscious

the part of the mind which is inaccessible to the conscious mind but which affects behavior and emotions. According to Sigmund Freud, it's a reservoir of mostly unacceptable thoughts, wishes, feelings, and memories.

Nonconscious

things happening in your body of which you are not aware, such as hormone secretion.

Biological Rhythms

the periodic physiological fluctuations our bodies go through.

Annual cycles

cycles that occur in our bodies on a yearly basis, such as SAD (Seasonal Affective Disorder - becoming depressed during the winter), or birds flying south for the winter and bears hibernating.

28-day cycles

cycles that occur every month. Ex. a woman's menstrual cycle.

Circadian rhythm

the biological clock; regular bodily rhythms that occur on a 24-hour cycle, such as body temperature or wakefulness.

Melatonin

a sleep-inducing hormone. The SCN causes the brain's pineal gland to decrease its production of melatonin in the morning or to increase it in the evening.

Adenosine

a neurotransmitter that causes drowsiness and the slowing of nerve cells. Caffeine is an antagonist that blocks the transmission of adenosine keeping us awake.

Sleep

a periodic, natural loss of consciousness. Throughout the night, the body experiences many sleep cycles, each one lasting around 90 minutes. Each cycle has 4 stages (NREM-1, NREM-2, NREM-3, REM).

Beta waves

waves of someone who is wide awake.

Alpha waves

the relatively slow brain waves of a relaxed, awake state.

NREM-1

the first stage that lasts about 5 minutes, emit theta waves, may experience hallucinations and hynagogic sensations (feelings of floating or falling).

Hallucinations

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

NREM-2

the second stage that lasts for about 20 minutes, clearly asleep and experience sleep spindles (random bursts of activity).

NREM-3

Known as slow wave sleep, the deepest stage of sleep in which it is hard to wake, emission of delta waves, sleep walking, bed wetting, etc. occur during this stage.

Delta waves

the larger, slow brain waves associated with deep sleep.

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.

NREM sleep

non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep.

REM rebound

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

Insomnia

a sleep disorder in which a person has recurring problems in falling or staying asleep.

Narcolepsy

a sleep disorder characterized by uncontrollable sleep attacks. These attacks are usually caused by excitement. 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 is associated with obesity. It is suggested people lose weight to help curb sleep apnea. Wearing an air pump while sleeping helps also.

Dreams

a sequence of images, emotions, and thoughts passing through a sleeping person's mind during REM sleep.

Information-processing (problem solving) theory

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

Physiological theory

regular brain stimulation from REM sleep may help develop and preserve neural pathways.

Activation-synthesis theory

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

Cognitive development theory

dream content reflects dreamers' cognitive development - their knowledge and understanding.

Memory consolidation

dreaming integrates newly encoded information into long-term memory.

Sensation

the process by which we receive physical energy from the environment and encode it into neural signals.

Perception

the process of organizing and interpreting sensory information.

Prosopagnosia

face blindness, seeing parts of the face but not being able to see the face as a whole.

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.

Absolute threshold

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

Difference threshold

the minimum difference between two stimuli required for detection 50% of the time. We experience this 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. Ex. hot tub no longer feels hot because you have gotten "used" to it.

Transduction

the conversion of one form of energy into another. In sensation, this is the transformation of sights, sounds, and smells into neural impulses our brain can interpret.

Wavelength

the distance from the peak of one light or sound wave to the next peak. Wavelengths in light waves determine the hue (color) and wavelengths in sound waves determine the pitch (sound).

Amplitude

the wave's height. It is measured from the peak of the wave to the trough of the wave. Amplitude measures the intensity of the wave. In light it determines the brightness of the color and in sound it determines the volume.

Vision

the sense of sight.

Pupil

the adjustable opening in the center of the eye through which light enters.

Iris

the ring of muscle tissue that forms the colored portion of the eye and that controls the size of the pupil opening.

Lens

the transparent structure behind the pupil that changes shape to help focus images on the retina. This process of the lens changing shape is called accommodation.

Retina

the light-sensitive inner surface of the eye that contains the receptor rods and cones plus layers of neurons that begin the processing of transduction for vision.

Rods

retinal receptors that detect black, white, and shades of gray that are necessary for peripheral and twilight vision when cones don't respond. The human eye has around 120 million rods.

Cones

retinal receptors that are concentrated near the center of the retina that detect colors and details and that function in the daylight or in well-lit conditions. The human eye has around 6 million cones.

Fovea

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

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 there are no receptor cells located there.

Bipolar cells

specialized neurons that connect the rods and cones w/the ganglion cells.

Ganglion cells

specialized neurons that connect to the bipolar cells.

Young-Helmholtz trichromatic (three-color) theory

the theory that the retina contains three different color receptors (red, green, and 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.

Acuity

sharpness of vision.

Nearsightedness

a condition in which nearby objects are seen clearly but distant objects are blurred because light rays reflecting from them converge in front of the retina.

Farsightedness

a condition in which distant objects are seen clearly but nearby objects are blurred because light rays reflecting from them strike the retina before converging.

Dichromatism

a person who is colorblind can see only two of the three primary colors (red, green, and blue).

Monochromatism

a person who is colorblind can see only one of the three primary colors (red, green, and blue).

Blindsight

a neurological condition where a person with damage to their primary visual cortex (causing cortical blindness) can still unconsciously respond to visual stimuli.

Audition

the sense of hearing.

Frequency

the number of complete wavelengths that pass a point in a given time.

Pitch

a tone's highness or lowness.

Timbre

the sound of a tone.

Outer ear

the part of the ear that traps sound waves and channels them through the auditory canal to the eardrum.

Pinna

the fleshy outside part of the ear.

Auditory canal

the canal in the outer part of the ear down which sound waves travel.

Eardrum

the tight membrane that vibrates when sound waves hit it.

Middle ear

the part of the ear that transmits the eardrum's vibrations through a piston made of three tiny bones (hammer, anvil, and stirrup) to the cochlea.

Ossicles

another name for the small bones in the middle ear.

Inner ear

the innermost part of the ear that contains the cochlea, semicircular canals, and vestibular sacs.

Basilar membrane

A membrane inside the cochlea which vibrates in response to sound.

Auditory nerve

the nerve that sends neural messages (via the thalamus) to the temporal lobe's auditory cortex.

Place theory

links pitch we hear with the place where the cochlea's membrane is stimulated.

Frequency theory

states that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone.

Volley principle

neural cells alternate firing.

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 of the cochlea's receptor cells or to the auditory nerves.

Cochlear implant

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

Epidermis

the outside layer of skin.

Dermis

the inside layer of skin.

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.

Phantom limb sensations

feeling sensations or movement in limbs that have been removed.

Nociceptors

sensory receptors that detect hurtful temperatures, pressure, or chemicals.

Endorphins

the body's natural painkillers.

Gustation

the sense of taste.

Papillae

structures on the tongue in which the taste buds are located.

Supertaster

someone who has a more sensitive sense of taste than the average person.

Medium taster

someone who has an average ability to sense different flavors.

Nontaster

someone who has a reduced ability to taste flavors.

Sensory interaction

the principle that one sense may influence another.

McGurk effect

a perceptual phenomenon which demonstrates an interaction between hearing and vision in speech perception.

Olfaction

the sense of smell.

Odorants

a chemical compound that has smell.

Olfactory bulb

the place in the nasal cavity where transduction occurs for smell.

Pheromones

Chemical signals that organisms release to communicate with other members of the species.

Vestibular sense

the sense of body movements and position, including the sense of balance.

Kinesthesis

the system for sensing the position and movement of individual body parts.