AP Psychology Unit 3

Sensation

The process by which sensory receptors detect stimulus energy from the environment.

Transduction

The conversion of sensory stimulus energy into electrical neural signals that the nervous system can process.

Perception

The brain’s process of organizing and interpreting sensory information to create a mental representation of the environment.

Psychophysics

The study of the relationship between physical characteristics of stimuli and psychological experiences.

Absolute threshold

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

Signal detection theory

An approach to detecting stimuli that considers both stimulus intensity and psychological factors such as expectations, motivation, and response bias.

Difference threshold

The minimum difference between two stimuli that can be detected 50% of the time.

JND (just-noticeable difference)

The smallest detectable difference between two stimuli.

Weber’s law

The principle that the JND is a constant proportion of the original stimulus, meaning noticeable changes depend on relative rather than absolute magnitude.

Adaptation

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

Wavelength

The distance between corresponding points on consecutive waves; for visible light it determines perceived hue.

Frequency

The number of wave cycles per second.

Amplitude

The height of a wave; for light it determines perceived brightness.

Pupil

The opening in the iris through which light enters the eye.

Iris

The colored muscle surrounding the pupil that controls its size and regulates how much light enters the eye.

Lens

The transparent structure that focuses incoming light onto the retina.

Accommodation

The adjustment of the lens’s shape to focus light from objects at different distances onto the retina.

Retina

The light-sensitive layer at the back of the eye containing photoreceptors.

Photoreceptors

Specialized retinal cells that detect light and convert it into neural signals.

Rods

Photoreceptors that are highly sensitive to light and primarily support vision in dim conditions.

Cones

Photoreceptors responsible for high-resolution color vision in bright light.

Optic nerve

A bundle of axons that carries visual information from the retina to the brain.

Blind spot

The area where the optic nerve exits the retina, containing no photoreceptors.

Fovea

A small central pit in the retina densely packed with cones that provides the sharpest vision.

Trichromatic theory

The theory that color perception results from the combined activity of three types of cones, each most sensitive to a different range of wavelengths.

Opponent-process theory

The theory that color information is processed through opposing channels

Feature detectors

Specialized neurons in the visual cortex that respond to basic visual features such as lines, edges, and angles.

Visual association cortex

Brain regions that combine visual information with prior knowledge to recognize and interpret objects.

Prosopagnosia

A visual disorder involving difficulty recognizing faces despite otherwise functional vision.

Dichromatism

A form of color vision deficiency in which one of the three cone types is absent or nonfunctional.

Monochromatism

A condition involving little or no color discrimination because vision relies on only one functional photoreceptor type or channel.

Blindsight

The ability to respond to visual stimuli without consciously perceiving them, usually following damage to the primary visual cortex.

Apparent motion

The perception of movement when separate stationary images or lights are presented rapidly in succession.

Phi phenomenon

A visual illusion in which separate stationary lights or images presented in rapid succession are perceived as continuous movement.

Ventral pathway (“what” pathway)

The visual pathway extending toward the temporal lobe that processes object identity and recognition.

Dorsal pathway (“where” pathway)

The visual pathway extending toward the parietal lobe that processes object location, spatial relationships, and movement.

Nociceptors

Sensory receptors that detect potentially damaging stimuli and contribute to pain perception.

Thermoreceptors

Sensory receptors that detect temperature, including heat and cold.

Taste receptors

Sensory cells that detect chemicals in food and contribute to taste perception.

Umami

The savory taste associated with glutamate, commonly found in foods such as meat and mushrooms.

Oleogustus

The taste associated with free fatty acids.

Supertasters

People who are highly sensitive to certain tastes.

Medium tasters

People with average taste sensitivity.

Nontasters

People who are less sensitive to certain tastes.

Gate-control theory

The theory that a neurological gate in the spinal cord can inhibit or allow pain signals to reach the brain.

Semicircular canals

Three fluid-filled structures in the inner ear that detect rotational head movements and help maintain balance.

Top-down processing

Processing that uses prior knowledge, expectations, and experiences to interpret sensory information.

Bottom-up processing

Processing that begins with incoming sensory information and builds toward perception.

Gestalt psychology

An approach to perception emphasizing that the brain organizes individual sensory elements into meaningful wholes.

Closure

The tendency to perceive incomplete figures as complete by mentally filling in missing information.

Figure and ground

The Gestalt principle of distinguishing an object of focus (figure) from its surrounding background (ground).

Proximity

The tendency to perceive objects that are close together as belonging to the same group.

Similarity

The tendency to group objects that share visual characteristics such as shape or color.

Consciousness

Moment-to-moment awareness of the external environment and one’s own thoughts, feelings, and behaviors.

Introspection

The examination and reporting of one’s own thoughts, feelings, and experiences.

Selective attention

Focusing conscious awareness on a particular stimulus while excluding other information.

Inattentional blindness

Failure to notice a visible stimulus because attention is focused elsewhere.

Change blindness

Failure to notice changes in a visual stimulus or environment.

Cocktail party effect

The ability to focus on one conversation while filtering out others yet notice personally relevant information, such as one’s name.

Automaticity

The ability to perform a task or process information with little conscious attention.

Cognitive unconscious

Mental processes that influence thoughts and behavior without conscious awareness or control.

Subliminal perception

Processing sensory information presented below the threshold of conscious awareness.

Default mode network

An interconnected network of brain regions active during rest and internally focused thought, such as mind-wandering and self-reflection.

Global workspace hypothesis

The hypothesis that conscious awareness occurs when information is integrated and made available across multiple brain regions and cognitive systems.

Circadian rhythm

The body’s approximately 24-hour biological cycle regulating bodily processes, including the sleep-wake cycle.

Jet lag

A disruption of the circadian rhythm caused by traveling across time zones.

Sleep

A naturally recurring state of altered consciousness characterized by reduced awareness and responsiveness to the environment.

EEG patterns

Patterns of electrical brain activity recorded by EEG that help identify states of consciousness and stages of sleep.

Beta waves

High-frequency, low-amplitude brain waves associated with alertness and active thinking while awake.

Alpha waves

Brain waves associated with relaxed wakefulness, particularly when resting with the eyes closed.

Hallucinations

Sensory experiences that occur without corresponding external sensory stimulation.

Delta waves

Very low-frequency, high-amplitude brain waves associated with deep non-REM sleep.

Non-REM sleep

The stages of sleep without rapid eye movements, ranging from light to deep sleep.

Hypnagogic sensations

Brief sensory experiences that occur while falling asleep (ex feeling like falling or muscle jerk)

Unihemispheric sleep

A sleep pattern in which one brain hemisphere experiences slow-wave sleep while the other remains relatively awake, as occurs in some animals.

Consolidation theory

The idea that sleep helps stabilize and strengthen newly formed memories.

Insomnia

A sleep disorder involving persistent difficulty falling asleep or staying asleep.

Sleep apnea

A sleep disorder involving repeated interruptions in breathing during sleep.

REM behavior disorder

A sleep disorder in which normal REM muscle paralysis is absent or incomplete, allowing a person to act out dreams.

Sleepwalking (somnambulism)

Performing activities while asleep, usually during deep non-REM sleep.

Night terrors

Episodes of intense fear and agitation during deep sleep, often involving screaming and limited awareness of the surroundings.

Narcolepsy

A sleep disorder involving sudden, uncontrollable episodes of falling asleep during normal waking activities.

Cataplexy

A sudden loss of muscle tone that can occur in people with narcolepsy.

REM rebound

The tendency to spend more time in REM sleep after being deprived of it.

Activation-synthesis hypothesis

The hypothesis that dreams result from the brain’s attempt to organize spontaneous neural activity during sleep into a coherent narrative.

Psychoactive drugs

Chemical substances that alter thoughts, feelings, perceptions, or behavior by affecting nervous system activity.

Caffeine

A stimulant that increases alertness.

Cocaine

A stimulant that increases the activity of neurotransmitters such as dopamine.

Heroin

An opioid that relieves pain and can produce pleasurable effects but has a high potential for addiction.

Opioids

Drugs that act on opioid receptors to reduce pain and may produce pleasurable effects.

Alcohol

A depressant that slows nervous system activity and can impair judgment and coordination.

Marijuana

A drug containing THC that can alter consciousness, perception, mood, and memory.

Tolerance

A diminished response to a drug after repeated use, potentially requiring greater amounts to produce the same effect.

Withdrawal

Physical and psychological symptoms that occur when a person with drug dependence reduces or stops drug use.

Addiction

A compulsive pattern of substance use despite harmful consequences.

Depressants

Psychoactive drugs that decrease nervous system activity and reduce arousal.

Stimulants

Psychoactive drugs that increase nervous system activity and alertness.

Psychedelics/hallucinogens

Drugs that alter perception, mood, and thought and can produce hallucinations.

Hypnosis

A social interaction involving focused attention and increased responsiveness to suggestions that may change perceptions, thoughts, feelings, or behaviors.

Hypnotic analgesia

A reduction in pain perception produced through hypnotic suggestion.