AP Psychology Midterm Review: Key Terms (Units 0, 1A, and 1B)

Comprehensive vocabulary flashcards covering key concepts, methodologies, biological bases of behavior, consciousness, sleep stages, and sensory systems for AP Psychology Units 0, 1A, and 1B.

Hindsight Bias

Believing, after learning an outcome, that you would have predicted it ("I knew it all along").

Overconfidence

Thinking we know more, or are more accurate, than we really are.

Hypothesis

A specific, testable prediction, usually drawn from a theory.

Falsifiability

A characteristic of a claim where some possible result could prove it wrong; scientific claims must be testable this way.

Operational Definition

A precise statement of exactly how a variable is measured or manipulated, so others can replicate the study.

Case Study

In-depth study of one person or small group. Cannot show cause and effect and may not generalize.

Naturalistic Observation

Watching and recording behavior in its natural setting without manipulating anything.

Survey

Collecting self-reported attitudes or behaviors, ideally from a random, representative sample.

Social-Desirability vs. Self-Report Bias

Social-desirability: answering to look good. Self-report: describing your own behavior inaccurately due to bad memory or misunderstanding.

Random Sample

A sample where every member of the population has an equal chance of being chosen, ensuring the sample represents the population.

Correlation

How closely two variables change together; coefficient $r$ runs from $-1.00$ to $+1.00$. Correlation does not equal causation.

Illusory Correlation

Seeing a relationship where none exists, or perceiving a stronger relationship than actually exists.

Experimental vs. Control Group

Experimental group: receives the treatment. Control group: does not receive the treatment (often given a placebo) and serves as the baseline for comparison.

Independent vs. Dependent Variable

Independent Variable (IV): the factor the researcher manipulates. Dependent Variable (DV): the outcome factor that is measured.

Random Sampling vs. Random Assignment

Random Sampling: determines who is in the study and allows generalization to the population. Random Assignment: assigns participants to groups by chance and allows the establishment of cause and effect.

Single-Blind vs. Double-Blind

Single-blind: participants do not know their assigned condition. Double-blind: neither participants nor researchers know the condition, controlling for both placebo effect and experimenter bias.

Quantitative vs. Qualitative

Quantitative: numerical data analyzed statistically. Qualitative: descriptive data such as words and themes.

Ethical Guidelines (Psychological Research)

Core research standards including informed consent (assent and parent consent for minors), right to withdraw, protection from harm, confidentiality, deception only when justified, debriefing afterward, and IRB approval before research begins.

Mean vs. Median vs. Mode

Mean: average score. Median: middle score. Mode: most frequent score.

Normal Curve

A symmetrical bell-shaped distribution where approximately $68\%$ of scores fall within 1 SD, $95\%$ within 2 SD, and $99.7\%$ within 3 SD.

Descriptive vs. Inferential Statistics

Descriptive: summarize and describe data. Inferential: determine if results apply to the larger population or are likely due to chance.

Statistical Significance

A statistical statement indicating that a result is unlikely to be due to chance (usually $p < .05$).

Evolutionary Psychology

The study of how behavior and mental processes evolved through natural selection.

Natural Selection

The principle that inherited traits that help an organism survive and reproduce are more likely to be passed on to succeeding generations.

Twin Studies

Research comparing identical twins (sharing $\approx 100\%$ of genes) and fraternal twins (sharing $\approx 50\%$ of genes) to estimate genetic versus environmental influence.

Epigenetics

The study of how environmental experience turns genes on or off, changing gene expression without changing DNA.

Sensory / Motor Neurons

Sensory (afferent) neurons: carry incoming messages from tissues to the brain and spinal cord. Motor (efferent) neurons: carry outgoing instructions from the brain and spinal cord to muscles and glands.

Interneurons

Neurons within the brain and spinal cord that connect sensory input to motor output.

Autonomic / Somatic NS

Autonomic nervous system: controls involuntary organs and glands. Somatic nervous system: controls voluntary movements of skeletal muscles.

Sympathetic / Parasympathetic

Sympathetic nervous system: arouses the body for fight-or-flight. Parasympathetic nervous system: calms the body (rest-and-digest).

Reflex Arc

An automatic spinal pathway involving sensory neuron $\rightarrow$ interneuron $\rightarrow$ motor neuron, occurring before the brain is involved.

Myelin Sheath

A fatty tissue layer encasing axons that insulates them and speeds neural impulses.

Glial Cells

Support cells in the nervous system that nourish, insulate, and protect neurons and clear metabolic waste.

Action Potential

A brief electrical impulse that travels down an axon once input passes the threshold (depolarization), followed by a refractory period back to resting potential.

All-or-None Principle

The principle that a neuron either fires at full strength or does not fire at all; a stronger stimulus results in more frequent firing and more neurons firing, not a stronger impulse.

Reuptake

The process by which the sending neuron reabsorbs excess neurotransmitters from the synaptic gap.

Dopamine

A neurotransmitter that influences movement, learning, attention, and reward.

Serotonin

A neurotransmitter that affects mood, hunger, sleep, and arousal.

Acetylcholine

A neurotransmitter that enables muscle contraction, learning, and memory.

Substance P

A neurotransmitter that carries pain signals.

Agonist / Antagonist

Agonist: a molecule that mimics or boosts the action of a neurotransmitter. Antagonist: a molecule that blocks a neurotransmitter's action.

Depressants vs. Stimulants

Depressants: psychoactive drugs that reduce or slow neural activity (e.g., alcohol). Stimulants: psychoactive drugs that speed up neural activity and body functions (e.g., caffeine, cocaine, nicotine, meth).

Tolerance vs. Withdrawal

Tolerance: requiring larger doses of a drug to experience the same effect. Withdrawal: the discomfort and distress that follow discontinuing the use of an addictive drug.

Addiction

Compulsive craving and use of a drug despite harmful consequences (substance use disorder).

Barbiturates vs. Opioids

Barbiturates: sedatives that reduce anxiety but impair memory and judgment. Opioids: drugs (morphine, heroin, fentanyl) that relieve pain by mimicking endorphins and slow breathing.

Hallucinogens

Psychoactive drugs that distort perceptions and evoke sensory images in the absence of sensory input.

Neuroplasticity

The brain's ability to change and reorganize itself across the lifespan after injury or experience (AP term: brain plasticity).

EEG / PET

EEG: scalp electrodes that record brain electrical wave patterns (measures function with precise timing). PET: tracks radioactive glucose consumption to show active brain regions (measures function).

MRI / fMRI

MRI: uses magnetic fields and radio waves to produce computer-generated images of brain structure. fMRI: reveals brain function by comparing successive MRI scans tracking blood flow.

Brainstem

The oldest part and central core of the brain; responsible for automatic survival functions.

Medulla

The base of the brainstem; controls heartbeat and breathing.

Thalamus

The brain's sensory relay station; directs messages to sensory receiving areas in the cortex for every sense except smell.

Reticular Formation

A nerve network in the brainstem that plays an important role in controlling arousal and alertness (AP term: reticular activating system).

Cerebellum

The "little brain" at the rear of the brainstem; processes sensory input, coordinates voluntary movement balance, timing, and procedural learning.

Amygdala

Two lima-bean-sized neural clusters in the limbic system linked to fear and aggression.

Hypothalamus

Limbic structure governing hunger, thirst, body temperature, sexual behavior, and reward; directs endocrine activity via the pituitary gland.

Hippocampus

A neural center located in the limbic system that helps process and form new explicit memories of facts and events.

Frontal Lobe

Portion of the cerebral cortex involved in planning, judgment, personality, and impulse control; contains the motor cortex for voluntary movement.

Parietal Lobe

Portion of the cerebral cortex that contains the somatosensory cortex (processes touch and body position) and enables spatial reasoning.

Occipital Lobe

Portion of the cerebral cortex lying at the back of the head that includes areas that receive information from the visual fields (visual cortex).

Temporal Lobe

Portion of the cerebral cortex lying roughly above the ears; houses the auditory cortex and processes sound and language.

Neurogenesis

The formation of new neurons, which occurs in some adult brain areas such as the hippocampus.

Corpus Callosum

The large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

Split-Brain Differences

Functional differences between hemispheres: Left specializes in language, logic, and literal meaning; Right specializes in faces, emotion, and spatial tasks. Each side controls the opposite side of the body and visual field.

Consciousness

Our subjective awareness of ourselves and our environment.

Parallel vs. Sequential Processing

Parallel processing: processing many aspects of a problem or stimulus at once, mostly unconscious and automatic. Sequential processing: processing one aspect of a stimulus at a time, conscious and slower.

Circadian Rhythm

The biological clock; regular bodily rhythms (such as temperature, sleepiness, and alertness) that occur on a roughly 24-hour cycle.

REM Sleep

Rapid-eye-movement sleep stage marked by vivid dreams; referred to as paradoxical sleep because the brain is active like when awake, but muscles are paralyzed.

NREM Stages 1-3

Non-REM sleep stages: N1 features light sleep and hypnagogic sensations; N2 is marked by sleep spindles; N3 is the deepest sleep characterized by slow delta waves.

Alpha vs. Delta Waves

Alpha waves: relatively slow brain waves of a relaxed, awake state. Delta waves: large, slow brain waves associated with deep N3 sleep.

Sleep Disruption Effects

Consequences of poor sleep that include impaired attention, memory, mood, judgment, reaction time, and immunity, as well as links to weight gain and depression.

Suprachiasmatic Nucleus

A pair of cell clusters in the hypothalamus that acts as the body's master clock; responds to light signals and controls melatonin production.

Insomnia vs. Narcolepsy

Insomnia: recurring problems in falling or staying asleep. Narcolepsy: a sleep disorder characterized by uncontrollable, sudden sleep attacks, sometimes directly into REM sleep.

REM Sleep Behavior Disorder

A sleep condition where normal REM muscle paralysis fails, causing individuals to physically act out their dreams.

Consolidation Theory

The view that sleep and dreams serve to sort, process, and store the day's experiences into long-term memories.

REM Rebound

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

Sensation vs. Perception

Sensation: the process by which sensory receptors and the nervous system detect stimulus energy. Perception: the process by which the brain organizes and interprets sensory input.

Top-Down vs. Bottom-Up Processing

Bottom-up processing: analysis that begins with the sensory receptors and works up to brain integration. Top-down processing: information processing guided by higher-level mental processes, expectations, and experience.

Transduction

Conversion of one form of energy into another; in sensation, transforming stimulus energies into neural impulses the brain can interpret.

Absolute vs. Difference Threshold

Absolute threshold: the minimum stimulus energy needed 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.

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, unchanging stimulation.

Wavelength

The distance from the peak of one light or sound wave to the peak of the next; in light, it determines hue (short wavelengths produce blue, long wavelengths produce red).

Rods vs. Cones

Rods: retinal receptors that detect black, white, and gray; necessary for peripheral and dim-light vision. Cones: retinal receptors concentrated near the fovea that detect fine detail and color in daylight.

Parallel Processing (Vision)

The brain's ability to process color, motion, form, and depth simultaneously across separate specialized areas.

Trichromatic vs. Opponent-Process Theory

Trichromatic theory: the retina contains three types of color receptors (red, green, blue) that combine to produce perception of any color. Opponent-process theory: opposing retinal processes (red-green, blue-yellow, black-white) enable color vision at later neurological stages.

Monochromatism

A condition in which a person has no working cones (or only one working cone type) and sees the world entirely in shades of gray.

Dichromatism

A form of color deficiency in which one cone type is absent or malfunctioning, making it difficult to distinguish specific colors (most commonly red and green).

Prosopagnosia

"Face blindness": a neurological inability to recognize familiar human faces despite having normal visual acuity.

Frequency

The number of complete sound wavelengths that pass a point in a given time; determines pitch (higher frequency produces higher pitch).

Cochlea

A coiled, bony, fluid-filled tube in the inner ear where hair cells transduce sound vibrations into nerve impulses.

Sensorineural vs. Conduction Hearing Loss

Sensorineural hearing loss: caused by damage to cochlear hair cells or auditory nerve fibers. Conduction hearing loss: caused by mechanical damage to the structural pathway that delivers sound to the cochlea (such as the eardrum or middle-ear bones).

Place vs. Frequency Theory

Place theory: pitch perception is determined by the specific place where the cochlea's basilar membrane is stimulated (explains high pitches). Frequency theory: pitch perception matches the frequency of neural impulses traveling up the auditory nerve (explains low pitches).

Gate Control Theory

The theory that the spinal cord contains a neurological "gate" that either blocks pain signals or allows them to pass on to the brain; the gate can be closed by other non-pain sensory input or descending brain activity.

Gustation

The sense of taste, composed of the basic sensations sweet, sour, salty, bitter, and umami.

Olfaction

The sense of smell; the only sensory modality whose neural pathways bypass the thalamus before reaching cortical targets.

Kinesthesia

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

Vestibular Sense

The sense of body movement and position, including balance, monitored by fluid movement in the semicircular canals of the inner ear.