Unit 1 AP psychology

2026

Heredity/Nature

refers to genetic or predisposed characteristics that influence physical, behavioral, and mental traits and processes

Environmental factors/nurture

refers to the external factors that one experiences, such as family interactions or education.

Evolutionary perspective (psychology)

explores how natural selection affects the expression of behavior and mental processes to increase survival and reproductive success.

Twin studies

The purpose of such research is usually to assess the relative contributions of heredity and environment to some attribute. Specifically, twin studies often involve comparing the characteristics of identical and fraternal twins and comparing twins of both types who have been reared together or reared apart. For example, two types of study have been used to investigate intelligence in twins: (a) identical twins reared apart—here, the genotypes (genetic makeups) are identical, but as there is no shared environment, any disparity in intelligence must result from the different environments; and (b) comparisons between identical twins reared together and fraternal twins reared together—here, one can assume that each pair of twins shares the same environment, but whereas the identical twins have 100% of their genes in common, the fraternal twins share only 50% of their genes, suggesting that if the identical twins show a greater similarity in intelligence than do the fraternal twins, the genes must play a role in that trait. The assumptions made in these studies are, however, never completely fulfilled. For example, the identical twins reared apart have had some common environment, if only their intrauterine experiences. Moreover, identical twins reared together usually have more similar environments than fraternal twins raised together.

Family studies

Research conducted among siblings, parents, or children to assess evidence for genetic links for characteristics or outcomes, often related to health or disease.

adoption studies

a research design that investigates the relationships among genetic and environmental factors in the development of personality, behavior, or disorder by comparing the similarities of biological parent-child pairs with those of adoptive parent-child pairs.

nature vs. nurture

the debate regarding the relative influences of genetic inheritance and environmental factors on human development

Charles Darwin

an English naturalist known for his contributions to the understanding of evolution through natural selection. He proposed that species evolve over time through the process of natural selection, where the organisms best adapted to their environment survive and reproduce.

Natural selection

the process by which organisms better adapted to their environment survive and reproduce, leading to the evolution of species over time.

Behavior genetics

the study of the role of genetic and environmental influences on behavior and personality traits

Mutation

a change in the DNA sequence that can lead to variations in traits among organisms, which may influence evolution

Genes

are segments of DNA that code for proteins and influence inherited traits and characteristics in an organism

Genome

the complete set of genetic material in an organism

Identical (monozygotic) twins

are twins that develop from a single fertilized egg, resulting in two genetically identical individuals

Fraternal (dizygotic) twins

are twins that develop from two separate fertilized eggs and are genetically distinct from one another

Interaction

the interplay that occurs when the effect of one factor (like environment) depends on another factor (such as heredity)

Epigenetics

the study of the chemical modifications of gene expression that do not involve changes to the underlying DNA sequence (environment can influence that expression)

Central nervous system (CNS)

includes the brain and spinal cord and interacts with all processes in the body

peripheral nervous system (PNS)

relays messages from the central nervous system to the rest of the body and includes the autonomic and somatic nervous system

Autonomic nervous system

governs processes that are involuntary and includes the parasympathetic and sympathetic nervous systems

somatic nervous systems

governs the processes that are voluntary

parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy

sympathetic nervous system

the division of the autonomic nervous system that arouses the body, mobilizing its energy

Nervous system

the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems

Nerves

bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs

sensory (afferent) neurons

neurons that carry incoming information from the sensory receptors to the central nervous system

Motor (efferent) neurons

neurons that carry outgoing information from the central nervous system to muscles and glands

Interneurons

neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs

Reflex

a simple, automatic response to a sensory stimulus, such as the knee-jerk reflex

Neuron

neural cells that transmit information

Cell body (soma)

the part of a neuron that contains the nucleus; the cell’s life-support center

Dendrites

a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body

Axon

the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

Myelin sheath

a fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speeds of neural impulses

Glial cells

cells that provide structures, insulation, communication, and waste transport

Action potential (Neural transmission)

most commonly occurs in an orderly, systematic way that involves the all-or-nothing principle, depolarization, refractory period, resting potential, reuptake, and threshold.

all-or-nothing principle

a neuron's reaction of either firing (with a full-strength response) or not firing

Depolarization

the loss of the inside/outside charge difference causes the next of axon channels to open, and then the next, like falling dominos

refractory period

in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

resting potential (polarization)

the positive-outside/negative-inside state

Synapse

the junction between the sending and receiving neuron; this tiny gap is called the synaptic gap or synaptic cleft

reuptake

a neurotransmitter's reabsorption by the sending neuron

Threshold

the level of stimulation required to trigger a neural impulse

Neurotransmitter

chemical messengers that cross the synaptic gaps between neurons

Excitatory

making action potential more likely

Inhibitory

making an action potential less likely

Dopamine

neurotransmitter that influences movement, learning, attention, and emotion. too much linked to schizophrenia; too little linked to tremors and decreased mobility in Parkinson's disease

Serotonin

neurotransmitter that affects mood, hunger, sleep, and arousal. too little is linked to depression

Norepinephrine

neurotransmitter that helps control alertness and arousal. undersupply can depress mood

Glutamate

a major excitatory neurotransmitter; involved in memory. too much can produce migraines or seizures

GABA

a major inhibitory neurotransmitter; undersupply linked to seizures, tremors, and insomnia

Endorphins

natural, opiate like neurotransmitters linked to pain control and pleasure

Substance p

a neuropeptide that acts as a neurotransmitter in the central and peripheral nervous systems.

Acetylcholine

neurotransmitter that enables muscle action, learning, and memory; the deterioration of ACh-producing neurons is connected to Alzheimer's disease

Hormones

outside of the nervous system they perform actions similar to neurotransmitters

Adrenaline

triggers fight-or-flight response

oxytocin

Oxytocin is a hormone that plays a key role in social bonds and human behaviors, including: Sexual arousal, Recognition, Trust, Romantic attachment, Parent-infant bonding

psychoactive drugs

can influence neurotransmitter function (block, encourage, or discourage)

agonists

encourage neural firing

antagonists

discourage neural firing

Endocrine system

the body’s slow chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream

Adrenal gland

in moments of danger the autonomic nervous system orders these glands to produce hormones like epinephrine and norepinephrine

Pituitary gland

referred to as the mastery gland that regulates other glands and hormones

Oxytocin

a hormone, often associated with social bonding and childbirth

stimulants

caffeine and cocaine, typically causes increased neural activity

Substance use disorder

a disorder characterized by continued substance use despite resulting life disruption

depressants

alcohol, typically causes decreased neural activity

hallucinogens

marijuana, typically causes distortions in perception and/or cognition

opioids

heroin, typically acts as a pain reliever

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the used to take larger and larger doses before experiencing the drug's effect

addiction

prompts user to crave the drug, to continue use despite adverse consequences, and to struggle when attempting to withdraw from it

withdrawal symptoms

the discomfort and distress that follow discontinuing an addictive drug or behavior

Barbiturates

drugs that depress the CNS activity, reducing anxiety but impairing memory and judgment

Near death experience

an altered state of consciousness reported after a close brush with death; often similar to drug-induced hallucinations

Brain stem (include pieces + medulla)

generally controls basic functioning such as breathing and heart rate

Reticular activating system

along with the brain's reward center generally control some voluntary movement, eye movement, and some types of learning, cognition, and emotion.

Brain's reward center (hypothalamus)

along with the reticular activating system generally control some voluntary movement, eye movement, and some types of learning, cognition, and emotion.

Cerebellum

generally controls coordination of muscle movement, balance, and some forms of procedural memory

Cerebral cortex

divided into two hemispheres and includes the limbic system, corpus callosum, and the lobes of the cortex

Limbic system

the thalamus, hypothalamus, pituitary gland, hippocampus, amygdala; associated with emotions and drives

Thalamus

the brain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Hypothalamus

a neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward

Pituitary gland

master endocrine gland

Hippocampus

a neural center located in the limbic system; helps process for storage explicit memories of facts and events

Amygdala

2 lima bean sized neural clusters in the limbic system; linked to emotion

Corpus callosum

the fibers connecting the two cerebral hemispheres

Lobes of the cortex

occipital lobes, temporal lobes, parietal lobes, frontal lobes

Occipital lobes

generally control visual information processing and are located in the rear of the brain

Temporal lobes

generally control auditory and linguistic processing and are located on the sides of the brain

Parietal lobes

generally control association areas and the somatosensory cortex; found in the back crown of the brain

Association areas

processes and organize information; involved in higher mental functions usch as learning, remembering, thinking, and speaking

Somatosensory cortex

processes touch sensitivity

Frontal lobes

located just behind the forehead, generally control linguistic processing, higher-order thinking, and executive function

Motor cortex

located at the rear of the frontal lobes and controls most types of skeletal movement

Split brain

reveals that the right and left hemispheres of the brain may specialize in different activities and functions

Left hemisphere

location of the areas of the brain that affect language

Broca's area

area responsible for speech production

Wernicke's area

area responsible for speech comprehension

Aphasia

disorder that results from damage to Broca/Wernicke's area