AP Psychology Comprehensive Review: Units 1-5 and Research Methods
Core Foundations of Psychology
The Central Question: Psychology begins with the debate of nature versus nurture: Are humans shaped more by biology (nature) or by experience (nurture)?
Psychological Consensus: Psychologists conclude it is always a combination of both. Genes provide predispositions—a higher statistical likelihood of developing specific traits or conditions—while the environment determines which of these predispositions are actually expressed.
Researching Nature and Nurture:
* Twin Studies: Researchers compare identical twins (who share of their genetic makeup) with fraternal twins (who share approximately of their genes).
* Adoption Studies: These compare adopted children to both their biological parents (nature) and their adoptive parents (nurture).
* Family Studies: These examine trait patterns across various relatives to see how traits cluster within lineages.
* Evolutionary Perspective: This argues that behaviors aiding survival and reproduction were passed down through natural selection.
* Historical Caveat: This perspective has been dangerously misapplied through eugenics, the practice of forcibly sterilizing individuals deemed to have undesirable traits.
Biological Basis of Behavior: Nervous and Endocrine Systems
The Central Nervous System (CNS): Occupying the top of the chain, it includes the brain and spinal cord. The spinal cord is capable of handling simple reflex arcs independently without consulting the brain.
The Peripheral Nervous System (PNS): This links the CNS to the rest of the body.
* Sensory Neurons: Carry information into the CNS.
* Motor Neurons: Carry commands out to the body.
* Somatic System: Manages deliberate, voluntary movements (e.g., raising a hand, walking).
* Autonomic System: Manages automatic functions (e.g., heartbeat, digestion, pupil dilation).
* Sympathetic Nervous System: Acts as the "gas pedal," preparing the body for emergencies (fight or flight).
* Parasympathetic Nervous System: Acts as the "brake," returning the body to a state of homeostasis.
The Endocrine System: This system sends chemical messages called hormones through the bloodstream.
* Pituitary Gland: Known as the master gland, it directs other glands and is itself controlled by the hypothalamus.
Neural Communication and Anatomy
Structure of the Neuron:
* Dendrites: Branch-like structures that gather incoming signals.
* Cell Body (Soma): Integrates inputs and determines if the signal should be forwarded.
* Axon: The long fiber through which the message travels.
* Myelin Sheath: A fatty layer produced by glial cells that insulates the axon. It speeds up transmission by forcing the signal to jump between gaps known as Nodes of Ranvier through a process called saltatory conduction.
* Axon Terminal: The end of the neuron that passes the message to the next cell. * Deterioration: When myelin breaks down, conditions like Multiple Sclerosis (MS) or Myasthenia Gravis occur, leading to impaired neural communication.
Types of Neurons:
* Sensory Neurons: Shuttle info toward the brain.
* Motor Neurons: Fly instructions outward to muscles.
* Interneurons: Handle the internal computing between the two.
The Neural Impulse:
* Resting Potential: The idle state of a neuron where it carries a negative internal charge.
* Threshold: The critical level of stimulation required to trigger a response. *
Action Potential: The electrical impulse that fires once the threshold is met. * Depolarization: The internal charge flips to positive.
* Repolarization: The charge returns to negative.
* Refractory Period: A brief phase where the neuron cannot fire again.
* All-or-None Principle: A neuron either fires or it doesn't; partial signals do not exist. Intensity (e.g., a whisper vs. a shout) is communicated by the frequency of firing and the number of neurons recruited.
Neurotransmitters and Pharmacology
Synaptic Transmission: The electrical signal triggers the release of neurotransmitters (NTs) from vesicles into the synaptic cleft (the gap between neurons) to bind with receptor sites on the next neuron's dendrites.
Reuptake: The process by which the sending neuron vacuums up leftover neurotransmitters to terminate the signal.
Agonists vs. Antagonists:
* Agonists: Mimic or increase the effect of a neurotransmitter.
* Antagonists: Block receptors, preventing the neurotransmitter from binding.
* Reuptake Inhibitors: Prevent the cleanup of NTs, leaving them in the synapse longer (e.g., SSRIs for serotonin, Cocaine for dopamine).
Essential Neurotransmitters (The "Big 8"):
* Acetylcholine (ACh): Involved in voluntary muscle movement and memory. A deficiency is linked to Alzheimer’s disease.
* Dopamine: Powers pleasure circuits and movement. Excess is linked to Schizophrenia; deficit is linked to Parkinson’s (tremors).
* Serotonin: Regulates mood, sleep, and appetite. A shortage is the biological basis for Depression.
* GABA: The main inhibitory NT that quiets neural activity. Lack of GABA leads to anxiety and seizures.
* Glutamate: The main excitatory NT involved in learning.
* Endorphins: Built-in pain relief. Opioid drugs hijack these receptors. * Norepinephrine: Manages alertness and stress response. Excess causes jitters; deficit causes drainage.
* Substance P: Transmits pain messages to the brain.
Key Hormones: These are slower than NTs and reach the whole body through the blood.
* Adrenaline: Fight or flight.
* Leptin: Fat-released signal for fullness.
* Ghrelin: Stomach-released signal for hunger.
* Melatonin: Pineal gland-released signal for sleep.
* Oxytocin: Promotes social bonding.
Drug Categories: All psychoactive drugs operate as agonists, antagonists, or reuptake inhibitors. Categories include Stimulants, Depressants, Hallucinogens, and Opioids. Extended use leads to tolerance and withdrawal.
Brain Structure and Function
Evolutionary Hierarchy: The brain is structured from oldest (bottom) to newest (top).
* Medulla: At the base; controls life-sustaining functions like breathing and heart rate. Damage is usually fatal.
* Pons: Bridges brain regions and regulates sleep.
* Reticular Activating System (RAS/RA): Governs arousal and filters sensory information.
* Cerebellum: Smooths coordination, supports balance, and stores muscle memory (procedural skills). It refines movement but does not initiate it.
The Limbic System (Emotional/Memory Hub):
* Thalamus: The sensory relay station for all senses except smell.
* Olfactory Bulb: Processes smell; it bypasses the thalamus and goes directly to emotional centers, explaining why scents trigger vivid memories. *
Hypothalamus: Maintains homeostasis (hunger, thirst, temperature) and controls the pituitary gland.
* Amygdala: Fear and threat detection.
* Hippocampus: Converts short-term memories into long-term ones. Damage causes anterograde amnesia (inability to form new memories).
The Cerebral Cortex (Complex Thinking):
* Frontal Lobe: Prefrontal cortex (decisions/planning), Motor cortex (movement), and Broca’s Area (speech production; damage causes halting speech).
* Parietal Lobe: Somatosensory cortex mapping body sensitivity.
* Temporal Lobe: Hearing and Wernicke’s Area (language comprehension; damage causes fluent but nonsensical "word salad").
* Occipital Lobe: Vision.
* Corpus Callosum: The bundle of fibers connecting the two hemispheres. Split-brain research (on patients with a severed connection) reveals hemispheric specialization.
Neuroplasticity: The brain's ability to reroute around damage, which is most prominent in childhood but occurs throughout life.
Consciousness, Sleep, and Dreams
Circadian Rhythm: A cycle entrained by light.
Sleep Stages: * REM (Rapid Eye Movement): Known as "paradoxical sleep" because brain waves look like wakefulness while the body suffers muscle atonia (paralysis). This is where vivid dreaming occurs. REM rebound occurs after deprivation.
* NREM-1: Lightest stage; theta waves, hypnogogic sensations (falling, seeing patterns).
* NREM-2: Theta waves; accounts for the longest proportion of sleep.
* NREM-3: Deep slow-wave sleep; delta waves. Growth hormone is released. Sleepwalking (somnambulism), sleep-talking, and night terrors occur here.
Dream Theories: * Activation Synthesis: The brainstem fires randomly, and the cortex improvises a story to make sense of it.
* Consolidation Theory: Sleep replays and strengthens memories from the day.
Sleep Disorders: * Insomnia: Difficulty falling/staying asleep.
* Narcolepsy: Sudden, uncontrollable REM sleep attacks.
* Sleep Apnea: Repeated breathing cessation during sleep. *
REM Behavior Disorder: Failure of normal REM paralysis.
Sensation and Perception
Sensation: Detecting physical stimuli and converting it into neural signals (transduction).
Perception: The brain's interpretation of those signals.
Thresholds: * Absolute Threshold: Minimum stimulus detectable of the time. * Weber’s Law: The Just Noticeable Difference (JND) is a constant proportion (e.g., you notice vs , but not vs ).
* Signal Detection Theory: Detection depends on psychological state (motivation, expectation).
* Sensory Adaptation: Tuning out constant stimuli to focus on changes.
Vision: * Photoreceptors: Rods (; periphery, dim light, motion) and Cones (; fovea, color, detail).
* Color Theories: Trichromatic Theory (RGB cones at the receptor level) and Opponent-Process Theory (opposing pairs like red-green at the ganglion level; explains afterimages).
* Anatomy: Cornea, Lens (accommodation focuses the image), Retina, and the Blind Spot (where the optic nerve leaves the eye).
Hearing: Sound waves enter the ear, ossicles amplify vibrations, and hair cells in the basilar membrane (inside the cochlea) transduce them.
* Pitch Theories: Place Theory (high pitch), Frequency Theory (low pitch), and Volley Theory (mid-range).
The Other Senses:
* Taste (Gustation): Sweet, sour, salty, bitter, umami, oleogustus.
* Pain: Gate Control Theory suggests the spinal cord has a "gate" that can be closed by competing input. Substance P carries pain signals.
* Proprioception: Vestibular Sense (balance; semicircular canals) and Kinesthesia (body position; muscle/joint receptors).
Cognitive Psychology: Memory, Thinking, and Intelligence
Processing Models:
* Bottom-Up Processing: Raw sensory data with no expectations.
* Top-Down Processing: Prior knowledge and context guide interpretation (e.g., using schemas or perceptual sets).
* Cocktail Party Effect: Selective attention allows you to hear your name in a crowd.
* Attention Failures: Inattentional Blindness (missing the "gorilla") and Change Blindness (missing visual changes).
Memory Storage: * Multi-Store Model: Sensory memory (Iconic: ; Echoic: few seconds) Short-term (approx. items, ) Long-term.
* Explicit Memory: Conscious facts (semantic) and personal events (episodic). * Implicit Memory: Unconscious skills (procedural) and priming. * Biological Basis: Long-Term Potentiation (LTP) is the strengthening of synapses based on recent patterns of activity.
Encoding and Retrieval: * Self-Reference Effect: Memory is strongest for things related to the self. * Spacing Effect: Distributed practice is better than cramming.
* Testing Effect: Retrieving information is better than rereading it.
* Serial Position Effect: Primacy (remembering beginnings) and Recency (remembering endings).
Forgetting: Proactive Interference (old blocks new) and Retroactive Interference (new blocks old).
* Misinformation Effect: Loftus showed that leading questions (using "smash" vs "hit") can alter memory.
Intelligence: * Theories: Spearman’s G (one general factor), Gardner’s Multiple Intelligences ( types), and Sternberg’s Triarchic (Analytic, Creative, Practical). * The Flynn Effect: IQ scores have risen about points per decade due to environmental factors.
* Assessments: Reliability (consistency), Validity (accuracy), and Standardization.
Development and Learning
Learning Theories: * Classical Conditioning (Pavlov): Pairing a Neutral Stimulus with an Unconditioned Stimulus (UCS) to create a Conditioned Response (CR). Example: Little Albert (conditioned fear).
* Operant Conditioning (Skinner): Shaping behavior through Consequences. * Positive Reinforcement: Adding a reward to increase behavior. * Negative Reinforcement: Removing a negative stimulus to increase behavior. * Reinforcement Schedules: Variable Ratio (unpredictable numbers) is most resistant to extinction (e.g., slot machines).
* Social Learning (Bandura): Learning by observation (Bobo Doll experiment).
Developmental Stages: * Piaget's Cognitive Stages: Sensory-motor, Pre-operational, Concrete operational, Formal operational. Tools include Assimilation (fitting info into schemas) and Accommodation (changing schemas). * Vygotsky: Focused on the Zone of Proximal Development (ZPD) and Scaffolding.
* Erikson’s Psychosocial Stages: stages representing crises from Trust vs. Mistrust to Integrity vs. Despair.
* Attachment: Mary Ainsworth's Strange Situation identified Secure, Avoidant, Anxious, and Disorganized styles. Harry Harlow proved contact comfort is more important than food.
Social Psychology and Personality
Atributions: * Fundamental Attribution Error: Overestimating personality and underestimating situation when explaining others' behavior.
* Self-Serving Bias: Crediting self for wins and blaming situation for losses.
Influence and Persuasion: * Cognitive Dissonance: Tension when behavior contradicts attitudes; we change one to resolve it. * Asch (Conformity), Milgram (Obedience), and Zimbardo (Social Roles). * Group Dynamics: Social Loafing (less effort in groups), Deindividuation (loss of self in a mob), and Groupthink (suppressing dissent for harmony).
Personality: * Freud: The Id (pleasure), Superego (morality), and Ego (reality). Defense mechanisms include Repression, Denial, Projection, Displacement, Reaction Formation, Rationalization, Sublimation, and Regression.
* The Big Five (OCEAN): Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism.
Mental and Physical Health
Stress: The General Adaptation Syndrome (GAS) stages: Alarm, Resistance, and Exhaustion.
Psychological Disorders: Classified via the DSM-5.
* Anxiety Disorders: GAD, Phobias, Social Anxiety, Panic Disorder. *
Depressive/Bipolar Disorders: MDD, PDD, Bipolar I/II.
* Schizophrenia: Positive symptoms (hallucinations, delusions) and negative symptoms (flat affect).
* Personality Disorders: Cluster A (odd), B (dramatic/antisocial), C (anxious/OCPD).
Therapies:
* CBT: Combines cognitive and behavioral techniques; most supported. * Humanistic (Rogers): Unconditional positive regard and active listening. * Biomedical: Antipsychotics (block dopamine), SSRIs (block serotonin reuptake), and Lithium (bipolar mood stabilizer).
Research Methods and Statistics
Experimental Design: Requires Random Assignment to establish cause and effect. Uses Independent Variables (manipulated) and Dependent Variables (measured).
Observational Research: Case studies, correlations (correlation causation), and naturalistic observation.
Statistics: * Measures of Central Tendency: Mean (average), Median (middle), Mode (most frequent).
* The Normal Curve (68-95-99.7 Rule): of data falls within standard deviation (), within , and within .
Ethics (IRB Rules): Informed consent, confidentiality, protection from harm, and debriefing.