Sensation, Perception, and States of Consciousness

sensation

sensation

The detection and encoding of sensory information from the environment.

transduction

The conversion of physical energy from stimuli into electrochemical signals for neural processing, except for smell.

perception

The process of organizing and interpreting sensory information to recognize meaningful objects and events.

top-down processing

A perceptual approach driven by experience and expectations, often quicker but more prone to errors.

bottom-up processing

A detail-oriented method of processing that builds perceptions from individual sensory input.

absolute threshold

The smallest amount of stimulation needed to detect a stimulus at least 50% of the time.

difference threshold

The minimum difference between two stimuli that can be detected at least 50% of the time, also known as the just noticeable difference (JND).

Weber's Law

The principle that two stimuli must differ by a constant minimum percentage to be perceived as different.

sensory adaptation

Reduced sensitivity to a constant stimulus over time, allowing focus on changes in the environment.

signal detection theory

A theory stating that detection of a stimulus depends on both the signal's strength and the individual's experience, expectations, and state of alertness.

Stroop Effect

The delay in reaction time when the color of words conflicts with their meaning, illustrating interference in perception.

selective attention

The process of focusing on specific stimuli while ignoring others, processing only a fraction of the information available.

cocktail party effect

The ability to focus on a single conversation in a noisy environment while filtering out background noise.

inattentional blindness

A lack of awareness of visible objects when attention is directed elsewhere.

change blindness

The failure to notice changes in a visual scene due to a lapse in attention.

prosopagnosia

A neurological condition, also known as face blindness, where individuals cannot recognize familiar faces.

visual transduction

The process by which photoreceptors in the retina convert light energy into neural signals.

blind spot

The area where the optic nerve exits the eye, lacking photoreceptors, thus creating a 'blind' spot.

Young-Helmholtz Trichromatic Theory

A color vision theory stating the retina has three types of cones sensitive to red, green, and blue light.

opponent-process theory

A theory that color vision is enabled by opposing retinal processes (e.g., red-green, blue-yellow) explaining afterimages.

feature detectors

Neurons in the visual cortex that respond to specific visual features such as edges, shapes, and movement.

parallel processing in vision

The brain's ability to simultaneously process color, motion, shape, and depth.

audition

The biological process by which the brain interprets sound waves processed by the auditory system.

transduction in hearing

The conversion of sound waves into neural signals within the cochlea of the inner ear.

sound localization

The brain's ability to determine where sounds originate based on time and intensity differences between ears.

place theory in hearing

A theory that high-pitched sounds are detected based on the specific area of the cochlea stimulated.

frequency theory

A theory suggesting that the rate of nerve impulses matches the frequency of a sound wave, explaining low-pitched sound perception.

volley theory

A theory for higher-pitched sounds where groups of neurons fire in rapid succession to achieve frequencies above 1,000 Hz.

conduction deafness

Hearing loss due to issues in the middle or outer ear that interfere with sound wave conduction.

sensorineural deafness

Hearing loss caused by damage to the cochlea or auditory nerve, often permanent.

consciousness

Awareness of oneself and one's environment, allowing for organized behavior.

circadian rhythm

A roughly 24-hour biological cycle regulating sleep, hormone release, and other bodily functions.

altered states of consciousness

States where there is a shift in mental activity, differing from normal wakefulness, such as sleep, meditation, or drug-induced states.

REM sleep

A stage of sleep characterized by rapid eye movements, vivid dreams, and muscle paralysis, critical for cognitive functions.

REM rebound

The increased duration and frequency of REM sleep following deprivation of REM sleep.

microsleep

Brief, involuntary episodes of sleep lasting from fractions of a second to 10 seconds, typically occurring in sleep-deprived individuals.

insomnia

A sleep disorder involving difficulty falling asleep, staying asleep, or achieving restful sleep.

sleep apnea

A disorder where breathing repeatedly stops during sleep, often leading to fatigue and increased health risks.

narcolepsy

A genetic disorder characterized by sudden, uncontrollable REM sleep attacks during the day, often triggered by emotions.

sleepwalking (somnambulism)

Engaging in activities while asleep, often during deep sleep, with no memory of the event.

night terrors

Episodes of intense fear during deep sleep, often resulting in screaming or thrashing without full awakening.

sleep paralysis

A condition where the body remains temporarily paralyzed when waking or falling asleep, often accompanied by hallucinations.

sleep deprivation

The condition of not getting enough sleep, leading to physical, emotional, and cognitive impairments.

Cornea

layer of transparent cells that protect the eye and focus rays as that enter the eye

optic nerve

the nerve that carries neural/electric impulses from the eye to the brain

Retina

layer of light sensitive cells (rods and cones), change light energy into an electric signal

jelly lens

to fine-focus rays on the retina by accommodation

iris

the colored portion of the eye around the pupil and controls the size of the pupil opening

pupil

opening in the center of the iris that lets light in