AP Psyc unit 1 part 2

Circadian rhythm

The biological clock that regulates bodily rhythms on a roughly 24-hour cycle.

Suprachiasmatic nucleus (SCN)

A pair of cell clusters in the hypothalamus that controls the sleep-wake cycle by using light signals to adjust melatonin production.

Alpha waves

Relatively slow brain waves characteristic of a relaxed, awake state.

NREM sleep

Non-rapid eye movement sleep, encompassing all sleep stages except REM.

Delta waves

Large, slow brain waves associated with deep sleep.

REM sleep

A recurring sleep stage characterized by vivid dreams, rapid eye movements, and relaxed postural muscles.

REM rebound

The tendency for REM sleep duration to increase following periods of REM sleep deprivation.

Hypnagogic sensations

Sensory experiences, such as feeling like you are falling or floating, that occur while transitioning into sleep.

Insomnia

A recurring problem in falling or staying asleep.

Narcolepsy

A sleep disorder characterized by sudden, uncontrollable sleep attacks, often causing the person to lapse directly into REM sleep.

Sleep apnea

A sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

REM sleep behavior disorder

A condition in which the normal paralysis associated with REM sleep is absent, causing individuals to physically act out dreams.

Dream

A sequence of images, thoughts, and emotions passing through the mind during sleep.

Sensation

The process by which sensory receptors and the nervous system detect and receive stimulus energies from the environment.

Perception

The process by which the brain organizes and interprets sensory input to recognize meaningful objects and events.

Transduction

The conversion of one form of energy into another, transforming physical sensory stimuli into neural signals.

Bottom-up processing

Sensory analysis that begins with the sensory receptors and moves upward to the brain for integration.

Top-down processing

Information processing guided by higher-level mental processes, such as prior knowledge, experience, and expectations.

Absolute threshold

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

Difference threshold (JND)

The minimum difference between two stimuli required for detection 50% of the time; also called the just noticeable difference.

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 to a stimulus as a consequence of constant, unchanging exposure.

Signal detection theory

A theory predicting how and when a person detects faint stimuli amid background noise, depending on factors such as attention, expectations, and fatigue.

Priming

The implicit activation of particular associations in memory, influencing subsequent perception or response.

Cornea

The transparent outer layer of the eye that protects the eye and bends light to provide focus.

Pupil

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

Iris

A ring of colored muscle tissue that controls the size of the pupil opening in response to light intensity.

Lens

The transparent structure behind the pupil that changes shape to focus images onto the retina.

Retina

The light-sensitive inner surface of the eye containing photoreceptor rods and cones, as well as neuron layers.

Rods

Retinal photoreceptors that detect black, white, and gray, necessary for peripheral and low-light vision.

Cones

Retinal photoreceptors concentrated near the center of the retina that detect fine detail and color in well-lit conditions.

Fovea

The central focal point in the retina around which the eye's cones cluster, providing the sharpest visual acuity.

Optic nerve

The neural pathway that carries visual information from the retina to the brain.

Blind spot

The point where the optic nerve leaves the eye, creating a gap in vision because no photoreceptors are present there.

Accommodation

The process by which the eye's lens changes curvature to focus near or distant images on the retina.

Trichromatic theory

The model proposing that the retina contains three types of color receptors, each primarily sensitive to red, green, or blue.

Opponent-process theory

The theory that opposing retinal processes (red-green, blue-yellow, black-white) enable color vision.

Audition

The physiological sense or act of hearing.

Frequency

The number of complete sound wave cycles that pass a point per second, which determines pitch.

Pitch

The experienced highness or lowness of a sound, determined by wave frequency.

Intensity

The amount of energy in a wave, perceived as loudness or brightness and determined by amplitude.

Wavelength

The physical distance between the crest of one wave and the crest of the next.

Middle ear

The air-filled chamber containing the hammer, anvil, and stirrup bones, which amplify and transmit sound vibrations to the cochlea.

Cochlea

A fluid-filled, coiled structure in the inner ear where hair cells convert sound vibrations into nerve impulses.

Place theory

The auditory theory linking the perception of pitch to the specific area of the cochlear membrane that is stimulated.

Frequency theory

The auditory theory that pitch perception corresponds to the rate of nerve impulses traveling up the auditory nerve.

Sensorineural hearing loss

Hearing impairment caused by damage to the cochlea's hair cell receptors or the auditory nerve.

Conduction hearing loss

Hearing impairment caused by structural damage to the mechanical system that conducts sound waves to the cochlea.

Gustation

The chemical sense of taste.

Olfaction

The chemical sense of smell.

Kinesthesis

The sensory system responsible for detecting the position and movement of individual body parts.

Vestibular sense

The sensory system that monitors the head's position and movement to maintain equilibrium and balance.

Gate-control theory

The theory that the spinal cord contains a neurological mechanism that either blocks pain signals or allows them to travel to the brain.

Sensory interaction

The principle that one sensory modality may influence another, such as aroma affecting taste perception.