Introduction to Psychology as a Science

Psychology is the scientific study of behavior and mental processes. As a science, it relies on systematic observation, experimentation, and empirical evidence to understand how humans and animals think, feel, and act.

• What makes psychology a science: Use of the scientific method, reliance on empirical data, and the formulation of testable hypotheses.

• Independent variable vs. dependent variable: The independent variable is manipulated by the researcher, while the dependent variable is measured to assess the effect of the manipulation.

• Example: In a study on the effect of sleep on memory, the amount of sleep is the independent variable, and memory performance is the dependent variable.

Biological Bases of Behavior

Neurotransmitters

Neurotransmitters are chemical messengers that transmit signals across synapses between neurons.

• GABA: The main inhibitory neurotransmitter in the brain, involved in reducing neuronal excitability.

• Serotonin: Regulates mood, appetite, and sleep; low levels are associated with depression.

• Endorphins: Natural painkillers produced by the brain; involved in pain relief and feelings of pleasure.

• Dopamine: Involved in reward, motivation, and motor control; imbalances linked to Parkinson's disease and schizophrenia.

• Norepinephrine: Influences arousal and alertness; involved in the body's stress response.

Major Brain Structures

• 4 Lobes of the Brain:

  • Frontal lobe: Planning, decision-making, voluntary movement.

  • Parietal lobe: Sensory processing, spatial orientation.

  • Temporal lobe: Auditory processing, memory.

  • Occipital lobe: Visual processing.

• Corpus callosum: Bundle of nerve fibers connecting the two hemispheres of the brain, enabling communication between them.

• Hemispheres of the brain: The brain is divided into left and right hemispheres, each specializing in different functions (e.g., language vs. spatial abilities).

• Hypothalamus: Regulates homeostasis, hunger, thirst, and the endocrine system.

• Hippocampus: Essential for the formation of new memories.

• Thalamus: Relay station for sensory information.

• Amygdala: Involved in emotion, especially fear and aggression.

• Reticular formation: Regulates arousal and alertness.

• Pons: Involved in sleep and arousal.

• Medulla: Controls vital functions such as breathing and heart rate.

• Endocrine glands: Glands that secrete hormones into the bloodstream (e.g., pituitary, adrenal glands).

Neurons and Neural Communication

• Parts of a neuron (4 main parts):

  • Dendrites: Receive signals from other neurons.

  • Cell body (soma): Contains the nucleus and organelles.

  • Axon: Transmits electrical impulses away from the cell body.

  • Axon terminals: Release neurotransmitters into the synapse.

• Synaptic vesicles and synapse: Vesicles store neurotransmitters, which are released into the synaptic gap to transmit signals.

• Myelin: Fatty sheath that insulates axons and speeds up neural transmission.

• All-or-none firing of neurons: A neuron either fires completely or not at all.

• Reuptake: Process by which neurotransmitters are reabsorbed by the presynaptic neuron.

• Action potential vs. resting potential:

  • Resting potential: The neuron's stable, negative charge when inactive.

  • Action potential: A brief electrical charge that travels down the axon when the neuron fires.

• Glial cells: Support, nourish, and protect neurons.

Research Methods in Psychology

• Peer-reviewed article: Scholarly article evaluated by experts before publication.

• Steps in the scientific method: Observation, hypothesis, experiment, data collection, analysis, conclusion.

• Single blind & double blind experiments:

  • Single blind: Participants do not know which group they are in.

  • Double blind: Neither participants nor experimenters know group assignments.

• Descriptive research: Observes and describes behavior without manipulating variables (e.g., naturalistic observation, laboratory observation).

• Experimental research: Involves manipulation of variables to determine cause and effect.

• Chemical agonist: Substance that mimics or enhances the action of a neurotransmitter.

• Chemical antagonist: Substance that blocks or reduces the action of a neurotransmitter.

• Operationalization/operational definition: Defining variables in measurable terms.

• Correlation coefficient: A statistical measure () of the relationship between two variables, ranging from -1 to +1.

• Positive and negative correlations:

  • Positive: Both variables increase or decrease together.

  • Negative: One variable increases as the other decreases.

Key Figures in Psychology

• Father of psychology: Wilhelm Wundt (established the first psychology laboratory).

• Mary Whiton Calkins: First female president of the APA; researched memory.

• Margaret Washburn: First woman to earn a PhD in psychology; studied animal behavior.

• Mary Cover Jones: Pioneer in behavior therapy; known for work on desensitization.

• Inez Beverly Prosser: First African American woman to earn a PhD in psychology.

• Ivan Pavlov: Known for classical conditioning experiments with dogs.

• John B. Watson: Founder of behaviorism.

• B.F. Skinner: Developed operant conditioning theory.

• Sigmund Freud: Founder of psychoanalysis.

Major Concepts and Theories

• Neuroplasticity: The brain's ability to change and adapt as a result of experience.

• Corticalization: Increase in the size and wrinkling of the cerebral cortex.

• Research from split brain patients: Studies on individuals with severed corpus callosum reveal lateralization of brain function.

• The bystander effect: Tendency for individuals to be less likely to help in an emergency when others are present.

• Experimenter effect: Unintentional influence of the experimenter's expectations on the results.

• Experimenter bias: When researchers' expectations influence their interpretation of results.

• Placebo effect: Improvement due to the belief in the efficacy of a treatment, not the treatment itself.

Professional Roles in Psychology

• Psychologist vs. Psychiatrist vs. Psychiatric social worker:

  • Psychologist: Holds a doctoral degree in psychology; cannot prescribe medication (in most states).

  • Psychiatrist: Medical doctor specializing in mental health; can prescribe medication.

  • Psychiatric social worker: Provides therapy and support services, often with a master's degree in social work.

Major Schools of Thought

• Behaviorism: Focuses on observable behavior and the effects of learning and environment.

• Psychoanalytic: Emphasizes unconscious processes and early childhood experiences (Freud).

• Structuralism vs. Functionalism:

  • Structuralism: Analyzes the basic elements of conscious experience (Wundt, Titchener).

  • Functionalism: Focuses on the purpose of consciousness and behavior (James).

Table: Comparison of Major Research Methods