Psychological Science and Biological Bases of Behavior

Posted on May 21, 2026 in Psychology and Sociology

Chapter 1: Introduction to Psychology

Psychology is the scientific study of behavior and mental processes.

  • Behavior: Observable actions.
  • Mental processes: Thoughts, feelings, memories, and perceptions.

Types of Research

  • Basic Research: Research conducted to gain knowledge or to support/refute theories.
  • Applied Research: Research used to solve real-world problems.

Four Goals of Psychology

  1. Describe: What is happening?
  2. Explain: Why is it happening?
  3. Predict: What will happen?
  4. Change: How can behavior be improved?

Historical Figures

  • Plato: Believed knowledge is inborn.
  • Aristotle: Believed knowledge comes from experience and the senses.
  • Ibn al-Haytham: Utilized experiments and observation.
  • René Descartes: Famous for the statement “I think, therefore I am.” He proposed dualism, the idea that the mind and body are separate.

The Research Process

  1. Develop a question.
  2. Create a hypothesis.
  3. Design a study and collect data.
  4. Analyze the data.
  5. Share findings.

Operational Definitions: A clear explanation of how a variable is measured in a study.

Population vs. Sample

  • Population: The entire group the researcher is interested in.
  • Sample: A smaller group chosen from a population.
  • Variables: Anything measurable that can change.

Descriptive Research

Descriptive research describes behavior but does not prove cause and effect.

  • Naturalistic Observation: Watching behavior in a natural setting. Weakness: Observer bias.
  • Case Study: An in-depth study of one person or a small group. Weakness: Findings cannot be generalized.
  • Survey Method: Uses questionnaires or interviews. Weakness: People may lie, or wording may influence answers.

Correlational Research

Studies the relationships between variables.

  • Positive Correlation: Both variables increase together. Example: More studying leads to higher grades.
  • Negative Correlation: One variable increases while the other decreases. Example: More exercise leads to less weight.
  • Zero Correlation: No relationship exists. Example: Height and weather.

Correlation does not equal causation: Just because two things relate does not mean one caused the other.

Experimental Research

This is the only type of research that proves cause and effect. Researchers manipulate variables while controlling all other factors.

  • Experimental Group: Receives the treatment or manipulation.
  • Control Group: Does not receive the treatment.

Research Ethics

  • Confidentiality: Protecting participant information.
  • Informed Consent: Ensuring participants understand what they are agreeing to.
  • Debriefing: Explaining the study after the experiment ends.
  • IRB (Institutional Review Board): A committee that approves research ethics.
  • Tuskegee Syphilis Study: Historically significant; Black men were misled and denied proper treatment for syphilis for decades.

Lobes of the Brain

  • Frontal Lobe: Responsible for decision making and personality.
  • Parietal Lobe: Responsible for the sense of touch.
  • Temporal Lobe: Responsible for hearing and memory.
  • Occipital Lobe: Responsible for vision.

Chapter 2: Biology and Behavior

  • Neuroscience: The study of the brain and the nervous system.
  • Biological Psychology: Studies how biology affects behavior.

Brain Study: Old vs. Modern

  • Phrenology: An old, incorrect idea that skull bumps reveal personality or brain function. It is essentially pseudoscience.
  • Modern Brain Technology: Used to study the living brain.
    • CT Scan: Shows brain structure.
    • MRI: Provides detailed brain images and structure.
    • EEG: Measures electrical activity.
    • PET Scan: Shows active brain areas.
    • fMRI: Shows both activity and structure.

The Neuron

The neuron is one of the most important psychology topics. A neuron is a nerve cell that sends messages.

Parts of the Neuron

  • Dendrites: Receive messages from other neurons. Think: “Dendrites DETECT.”
  • Cell Body (Soma): Contains the nucleus and keeps the neuron alive.
  • Axon: Carries messages away from the cell body. Think: “AXON = EXIT away.”
  • Myelin Sheath: A fatty coating around the axon. Function: Speeds up messages.
  • Nodes of Ranvier: Tiny gaps in the myelin sheath that help signals jump faster.
  • Axon Terminals: The end of the neuron; they release neurotransmitters to the next neuron.

Neural Communication

  • Resting Potential: The neuron is resting and ready to fire.
  • Action Potential: An electrical impulse traveling down the axon. This is the neuron “firing.”
  • All-or-None Principle: A neuron either fires completely or doesn’t fire at all; there is no halfway firing.
  • Neurotransmitters: Chemical messengers between neurons sent across the synapse.

Key Neurotransmitters

  • Dopamine: Reward and motivation.
  • Serotonin: Mood.
  • Acetylcholine: Movement and memory.

Signal Pathway

The message travels: Dendrites → Cell Body → Axon → Axon Terminals

The Nervous System

Central Nervous System (CNS)

  • Includes the brain and spinal cord.
  • Acts as the main control center.
  • Spinal Cord: Carries messages between the brain and the body.

Peripheral Nervous System (PNS)

  • Includes everything outside the CNS.
  • Connects the body to the brain and spinal cord.
  • Includes all nerves.

Divisions of the PNS

  • Somatic Nervous System: Controls voluntary movement. Example: Walking or raising your hand. Think: “Somatic = conscious control.”
  • Autonomic Nervous System: Controls involuntary functions. Example: Heartbeat, breathing, and digestion.

Autonomic Divisions

  • Sympathetic Nervous System: Fight-or-flight; activated during stress or emergencies. Effects: Heart rate increases, pupils dilate, and adrenaline is released. Think: “Sympathetic = STRESS.”
  • Parasympathetic Nervous System: Rest-and-digest; calms the body down. Effects: Slows heart rate and digestion resumes. Think: “Parasympathetic = PEACEFUL.”

Key Comparisons

  • CNS vs. PNS: The CNS consists of the brain and spinal cord; the PNS includes all other nerves.
  • Somatic vs. Autonomic: Somatic is voluntary; Autonomic is involuntary.
  • Sympathetic vs. Parasympathetic: Sympathetic activates the body; Parasympathetic calms the body.