AP Psych Notes

Unit 1: Biological Bases of Behavior

Scientific Foundations of Psychology

• Hypothesis: A specific, testable prediction about the relationship between two or more variables, derived from a theory. It sets up what you expect to happen in the experiment.

• Operational Definitions: A clear, precise definition of a variable in terms of how it will be measured or manipulated in a study. Important for replicating experiments.

• Data Collection Techniques: Methods like observations, interviews, surveys, or experiments to gather information systematically. The technique chosen affects the validity and reliability of the data.

• Population: The entire group of people or entities researchers are interested in studying. A sample is drawn from the population for practical reasons.

• Sample: A subset of the population that should represent the larger group. Random sampling helps avoid bias and ensures generalizability.

• Independent Variable (IV): The variable that is deliberately manipulated to test its effect on the dependent variable. It's what researchers control.

• Dependent Variable (DV): The outcome that is measured to see if it changes as a result of manipulating the IV. It’s the "effect" part of the cause-effect relationship.

• Extraneous Variables (EV): Any variables other than the IV that might affect the DV. These must be controlled to avoid confounding results.

• Confounding Variables: Specific extraneous variables that unintentionally vary with the IV, making it impossible to know if changes in the DV were due to the IV or the confounding variable.

• Experimental Group: The group that receives the treatment or the IV in an experiment. They are exposed to the condition being tested.

• Control Group: The group that does not receive the treatment and serves as a baseline comparison to the experimental group. This helps establish causality.

• Random Assignment: A process used in experiments to ensure that each participant has an equal chance of being assigned to either the control or experimental group, eliminating bias.

• Sampling Bias: Occurs when the sample does not accurately reflect the population, potentially skewing the results and limiting generalizability.

• Placebo Effect: When participants experience a perceived improvement in condition due to their expectations, even though they haven't received the active treatment.

• Social Desirability Bias: The tendency for participants to answer questions in a way that will be viewed favorably by others, often leading to inaccurate data.

• Halo Effect: A cognitive bias where our overall impression of a person influences how we feel and think about their specific traits. One positive trait makes us assume other positive qualities.

• Experimenter Bias: When researchers’ expectations subtly influence participants’ behaviors or the outcome of the study, leading to biased results.

• Double-Blind Procedure: Both participants and experimenters are unaware of who is in the control or experimental group, preventing bias from influencing results.

Other Research Methods

• Correlational Study: Research method that examines how two variables are related, but it does not imply causation. Correlation coefficients range from -1 to +1.

• Naturalistic Observation: Observing behavior in its natural environment without manipulation or intervention. It offers high external validity but lacks control over variables.

• Case Study: An in-depth, detailed examination of an individual or small group. Case studies can provide deep insights but lack generalizability.

• Survey: A self-report method where participants answer questions. Surveys are efficient for collecting large amounts of data, but are subject to biases like social desirability.

• Longitudinal Study: Studies the same individuals over a long period of time, allowing researchers to observe changes over time. These studies are time-consuming and costly but provide valuable developmental insights.

• Cross-Sectional Study: Compares individuals of different ages or stages at one point in time. Quicker than longitudinal studies, but can be affected by cohort effects.

Statistics in Research

• Mean: The average score of a data set. While it summarizes the data, it can be skewed by outliers.

• Median: The middle score in a data set, unaffected by extreme scores, making it a better measure in skewed distributions.

• Mode: The most frequent score in a data set. Sometimes there may be more than one mode, and it’s useful for categorical data.

• Range: The difference between the highest and lowest scores. It provides a rough measure of variability but is affected by extreme values.

• Standard Deviation: Measures how spread out scores are around the mean. A higher SD means more variability in the data, while a lower SD means the data points are closer to the mean.

• Percentile: Indicates the relative position of a score within a distribution, showing how a score compares to others.

• Normal Distribution/Curve: A bell-shaped curve where most scores fall near the mean, and fewer fall near the extremes. The mean, median, and mode are all equal in a perfectly normal distribution.

• Regression Toward the Mean: When extreme data points are followed by more typical data points closer to the average. This often happens due to random chance.

• Statistical Significance (p-value): Indicates whether an observed effect is likely due to chance. A p-value less than 0.05 typically means the results are significant.

• Effect Size: Shows how strong the relationship between two variables is. Larger effect sizes indicate a more meaningful or impactful relationship.

• Positive/Negative Skew: Skewness refers to the direction of the tail of the distribution. A positive skew has more low scores, while a negative skew has more high scores.

• Correlation Coefficient (r): A numerical value (-1 to +1) that represents the strength and direction of a relationship between two variables. A value close to ±1 indicates a strong relationship, while 0 indicates no relationship.

• Replication: Repeating a study to see if the same results can be achieved, which is crucial for validating findings.

• Meta-Analysis: A statistical procedure for combining the results of multiple studies on the same topic to derive a comprehensive conclusion.

Ethics in Research

• Tuskegee Syphilis Study: An unethical study where treatment was withheld from Black men with syphilis to observe the disease’s progression. Led to stricter ethical guidelines for research.

• Stanford Prison Experiment: Showed the power of situational factors in influencing behavior, but was highly criticized for ethical violations, including psychological harm to participants.

• Milgram Obedience Studies: Studied obedience to authority by having participants administer shocks to others. It raised significant ethical concerns about the stress placed on participants.

• Informed Consent: Participants must be informed about the nature of the research, including any risks, before agreeing to take part.

• Informed Assent: Similar to consent but applies to minors, who need the consent of a guardian and their own agreement to participate.

• IRB (Internal Review Board): A board that reviews and approves research involving human participants to ensure ethical standards are met.

• Debriefing: After the experiment, researchers must explain the purpose of the study to participants, including any deception that was used.

• Right to Withdraw: Participants have the right to leave the study at any point, without penalty.

Anatomy of a Neuron

• Neuron: The basic unit of the nervous system, responsible for transmitting information through electrical and chemical signals.

• Soma: The cell body of the neuron, containing the nucleus and organelles. It integrates incoming signals.

• Dendrites: Branch-like structures that receive messages from other neurons. More dendrites mean a higher capacity for communication with other neurons.

• Receptor Sites: Located on the dendrites, these are specific points where neurotransmitters bind, allowing signals to be received.

• Neurotransmitters (NTs): Chemicals that transmit signals across synapses. They bind to receptors on the postsynaptic neuron to either excite or inhibit its action.

• Axon: The long projection that transmits electrical impulses away from the soma toward other neurons, muscles, or glands.

• Terminal Branches/Bulbs: The ends of the axon where neurotransmitters are stored and released into the synapse.

• Myelin Sheath: A fatty layer that insulates the axon and speeds up the transmission of electrical signals. Damage to myelin (as in multiple sclerosis) can slow or block signal transmission.

• Schwann Cells: Produce the myelin sheath in the peripheral nervous system, critical for nerve regeneration.

• Glial Cells: Supportive cells that provide nourishment, remove waste, and help repair damage to neurons.

• Nodes of Ranvier: Gaps in the myelin sheath where ions can enter and exit the axon, allowing for the rapid transmission of electrical impulses through saltatory conduction.

• Presynaptic/Post-Synaptic Neurons: The neuron sending the signal (presynaptic) and the neuron receiving the signal (postsynaptic).

• Excitatory/Inhibitory Signals: Excitatory signals increase the likelihood of the neuron firing, while inhibitory signals decrease it.

Neurophysiology: The Action Potential

• Ion: Charged particles (such as K+, Na+, Cl-) that move in and out of the neuron to create electrical signals.

• Resting Potential: The electrical charge of a neuron when it is not active, typically -70mV inside the neuron, ready for action.

• Action Potential: A rapid reversal of charge that travels down the axon when a neuron fires. It is initiated when the threshold is reached.

• Refractory Period: A short time after an action potential during which the neuron cannot fire again, ensuring the action potential moves in one direction.

  • All-or-None Law: A neuron either fires at full strength or not at all—there is no "partial" firing.

• Depolarization: When the neuron’s internal charge becomes less negative (closer to zero), allowing the action potential to occur.

• Hyperpolarization: When the internal charge becomes more negative than resting potential, making it harder for the neuron to fire.

Neurotransmitters and Functions

• 1. Acetylcholine (ACh)

  • Functions: Involved in voluntary muscle movement, learning, memory, and sleep.

  • Excess: Linked to depression.

  • Deficiency: Leads to myasthenia gravis (muscle weakness), and linked to Alzheimer's disease due to memory loss.

  • Excitatory or Inhibitory?: Both (depending on location and receptors).

  • Mnemonic: Ace the Championship with Muscle and Memory (ACh helps with movement and learning).

• 2. Dopamine

  • Functions: Regulates voluntary and involuntary muscle movement, attention, motivation, and the brain's reward system (pleasure).

  • Excess: Linked to schizophrenia (hallucinations and delusions).

  • Deficiency: Leads to Parkinson’s disease (tremors, muscle rigidity).

  • Excitatory or Inhibitory?: Both (depending on pathway).

  • Mnemonic: Do it for the Prize (Dopamine is involved in Pleasure and Movement).

• 3. GABA (Gamma-Aminobutyric Acid)

  • Functions: Major inhibitory neurotransmitter; reduces anxiety and neural activity, promotes relaxation and sleep.

  • Excess: Rare, but could result in excessive sedation or drowsiness.

  • Deficiency: Associated with anxiety disorders, seizures, and insomnia.

  • Excitatory or Inhibitory?: Inhibitory.

  • Mnemonic: Get A Break from Anxiety (GABA calms you down).

• 4. Serotonin

  • Functions: Regulates mood, hunger, sleep, and arousal. Plays a role in well-being and happiness.

  • Excess: Can lead to serotonin syndrome (agitation, confusion, rapid heart rate).

  • Deficiency: Linked to depression, anxiety, and OCD.

  • Excitatory or Inhibitory?: Inhibitory.

  • Mnemonic: Sunny Side Up (Serotonin stabilizes mood and well-being).

• 5. Epinephrine (Adrenaline) / Norepinephrine (Noradrenaline)

  • Functions: Involved in the fight-or-flight response, increasing heart rate, blood flow, and energy. Norepinephrine also regulates alertness and arousal.

  • Excess: Can cause anxiety, high blood pressure, and rapid heartbeat.

  • Deficiency: Can result in fatigue, depression, and a lack of focus.

  • Excitatory or Inhibitory?: Excitatory.

  • Mnemonic: Energy for the Fight or Flight (Epinephrine and Norepinephrine kick in during stressful situations).

• 6. Endorphins

  • Functions: Natural painkillers, reduce pain perception, and promote feelings of pleasure and well-being (similar to opioids).

  • Excess: Can lead to an artificial sense of euphoria (similar to effects of drugs like morphine).

  • Deficiency: Can result in increased pain sensitivity, low tolerance for discomfort, and addiction to pain relievers.

  • Excitatory or Inhibitory?: Inhibitory.

  • Mnemonic: End the Pain with a Morphine-like boost (Endorphins block pain and make you feel good).

• 7. Glutamate

  • Functions: The primary excitatory neurotransmitter, crucial for memory, learning, and neural communication.

  • Excess: Can lead to excitotoxicity, contributing to neurological conditions like Alzheimer’s disease, stroke, and seizures.

  • Deficiency: Can lead to difficulty concentrating, mental exhaustion, and memory problems.

  • Excitatory or Inhibitory?: Excitatory.

  • Mnemonic: Glut of Memory (Glutamate helps with learning and memory).

Drugs and the Nervous System

• Reuptake: The process by which neurotransmitters are reabsorbed by the presynaptic neuron after transmitting a signal.

• SSRI (Selective Serotonin Reuptake Inhibitors): Block the reuptake of serotonin to increase its availability, commonly used to treat depression.

• Antagonists: Drugs that block or reduce the effects of a neurotransmitter.

• Agonists: Drugs that enhance or mimic the effects of a neurotransmitter.

• Psychoactive Drugs: Chemicals that alter perception, mood, and behavior by affecting neurotransmitter function.

  • Depressants: Slow down nervous system activity (e.g., alcohol).

  • Stimulants: Increase nervous system activity (e.g., caffeine, cocaine).

  • Hallucinogens: Cause perceptual distortions (e.g., LSD).

  • Opioids: Act on pain relief and pleasure pathways (e.g., morphine).

Nervous System Structure

• Central Nervous System (CNS): Composed of the brain and spinal cord, responsible for processing information and controlling most functions of the body.

• Peripheral Nervous System (PNS): Consists of sensory and motor neurons that connect the CNS to the rest of the body.

  • Somatic Nervous System: Controls voluntary movements of skeletal muscles.

  • Autonomic Nervous System (ANS): Regulates involuntary functions like heart rate, digestion, and respiration.

    • Sympathetic Division: Prepares the body for emergency responses (fight-or-flight).

    • Parasympathetic Division: Calms the body and conserves energy (rest and digest).

Brain Structures

• Hindbrain: Manages basic life functions.

  • Medulla: Regulates heart rate and breathing.

  • Pons: Involved in sleep and arousal.

  • Cerebellum: Controls coordination and balance.

• Midbrain: Coordinates movement and processes sensory information.

• Forebrain: Controls higher cognitive functions and emotions.

  • Limbic System: Emotional center of the brain.

    • Thalamus: Relays sensory information.

    • Hypothalamus: Regulates basic drives (hunger, thirst, temperature).

    • Amygdala: Involved in fear and aggression.

    • Hippocampus: Critical for memory formation.

• Cerebral Cortex: The wrinkled outer layer of the brain responsible for higher-order thinking, sensation, and voluntary muscle movement.

Hemispheres and Lobes

• Occipital Lobes: Process visual information.

• Parietal Lobes: Process sensory information related to touch, temperature, and body position.

• Temporal Lobes: Involved in auditory processing and language comprehension (Wernicke’s area).

• Frontal Lobes: Involved in reasoning, problem-solving, planning, and motor control. Broca’s area is crucial for speech production.

Neuroplasticity

• Neuroplasticity: The brain’s ability to reorganize itself by forming new neural connections, especially after injury.

• Split-Brain Patients: Individuals whose corpus callosum has been severed, often studied to understand the distinct functions of the brain’s hemispheres.

Brain Imaging Techniques

• CT Scan: Uses X-rays to create detailed images of the brain’s structure.

• MRI: Uses magnetic fields and radio waves to create detailed images of the brain’s soft tissue.

• fMRI: A functional MRI that shows both the structure and activity of the brain by measuring blood flow.

• PET Scan: Measures brain activity by detecting radioactive glucose uptake.

• EEG: Records electrical activity in the brain, useful for studying brain waves, especially in sleep research.

Endocrine System

• Hormones: Chemical messengers that travel through the bloodstream to regulate bodily functions, such as growth, metabolism, and mood.

• Endocrine System: A series of glands that release hormones into the bloodstream.

  • Oxytocin: Promotes social bonding, maternal behaviors, and trust.

  • Adrenaline (Epinephrine): Prepares the body for fight-or-flight responses.

  • Leptin: Regulates hunger by signaling when the body is full.

  • Ghrelin: Signals hunger, increasing food intake.

  • Melatonin: Regulates sleep-wake cycles, released in response to darkness.

Genetic Heritability

• Chromosomes/Genes: Chromosomes are strands of DNA that contain genes, which code for proteins and determine traits.

• Polygenic Traits: Traits influenced by multiple genes, such as height or skin color.

• Epigenetics: The study of how environmental factors can alter gene expression without changing the DNA sequence itself.

Evolutionary Psychology

• Evolutionary Psychology: Examines how natural selection has shaped behavior that aids in survival and reproduction.

• Adaptation: A trait that increases the likelihood of survival and reproduction, passed down to future generations.

States of Consciousness and Sleep

• Consciousness: Awareness of one’s own existence, thoughts, and surroundings.

• Hypnosis: A state of focused attention and increased suggestibility.

• Circadian Rhythms: Biological cycles that occur roughly every 24 hours, regulating sleep, hunger, and hormone release.

• Sleep Stages:

  • NREM-1: Light sleep where you drift in and out of sleep.

  • NREM-2: Deeper sleep with sleep spindles (bursts of brain activity).

  • NREM-3: Deep sleep, characterized by slow delta waves.

  • REM Sleep: The stage where dreaming occurs, with rapid eye movement and high brain activity.

• Sleep Disorders:

  • Insomnia: Difficulty falling or staying asleep.

  • Narcolepsy: Sudden sleep attacks during waking hours.

  • Sleep Apnea: Breathing temporarily stops during sleep.

  • Night Terrors/Somnambulism: Occur during deep sleep (NREM-3) and can involve intense fear or sleepwalking.

Sensation and Perception

• Sensation: The process by which sensory receptors receive stimuli from the environment.

• Perception: The process of organizing and interpreting sensory information, allowing us to recognize meaningful objects and events.

  • Bottom-Up Processing: Begins with sensory receptors and works up to the brain’s integration of sensory information.

  • Top-Down Processing: Guided by higher-level mental processes, as when we construct perceptions based on experiences and expectations.

Visual System

• Cornea: The clear outer covering of the eye that helps focus light.

• Pupil: The adjustable opening in the center of the eye that controls the amount of light entering.

• Lens: Focuses light onto the retina by changing shape, a process called accommodation.

• Retina: Contains photoreceptors (rods and cones) that detect light and color.

  • Rods: Detect light intensity and are more active in low-light conditions.

  • Cones: Detect color and fine detail, concentrated in the fovea.

• Optic Nerve: Carries neural impulses from the eye to the brain for processing.

• Blind Spot: The point where the optic nerve leaves the retina, creating an area without visual receptors.

Auditory System

• Cochlea: A spiral-shaped structure in the inner ear that contains the basilar membrane and hair cells, which transduce sound waves into neural signals.

• Place Theory: Different frequencies cause different areas of the cochlea’s basilar membrane to vibrate, explaining pitch perception.

• Frequency Theory: Pitch is perceived based on the frequency of sound waves and how fast the entire basilar membrane vibrates.

Taste, Smell, and Touch

• Gustatory System: Detects the five basic tastes—sweet, salty, sour, bitter, umami—through taste buds on the tongue.

• Olfactory System: Detects smells through chemical receptors in the nasal cavity.

• Touch Receptors:

  • Mechanoreceptors: Respond to pressure, texture, and vibration.

  • Thermoreceptors: Detect changes in temperature.

  • Pain Receptors: Respond to tissue damage or extreme stimuli.

  • Proprioceptors: Provide information about the position and movement of the body.