Chapter 1: What is Psychology?

Intro to Psychology

The history of modern psychology

  • Great thinkers in history (Aristotle, Zoroaster) raised “psychological” questions, but they answered them with anecdotes instead of evidence.
  • Phrenology, the pseudoscientific belief that bumps on the skull could tell us about a person’s personality traits, became popular in the 1800s.
    • Example of anecdotal “psychology” not working.
  • In 1879, Wilhelm Wundt established the first psychological lab.
    • Volunteers were trained to carefully observe and analyze their own sensations.
    • Wundt is credited for initiating the movement to make psychology a science.
  • Functionalism emphasized the purpose of behavior, as opposed to its description.
    • Ask how an action helps a person/animal adapt to the environment.
  • Freud was a physician who became convinced that depression, nervousness, etc came from childhood conflicts and traumas that were too threatening to be remembered consciously.
    • For example, sexual feelings for a parent.
    • Eventually his ideas evolved into a broad theory of personality and a method of psychotherapy, both known as psychoanalysis.
    • Freud did not rigorously test his theories.

Major perspectives in psychology


  • Hormones
  • Chemical imbalances
  • Illness

Evolutionary psychology: how behavior that was useful in our evolutionary past may be reflected in our present behaviors, mental processes, and traits.


  • How environments and experience affect humans and animals
  • People learn by imitating others and by reacting to surrounding events


  • Focuses on what goes on inside people’s heads


  • Focuses on social and cultural forces outside the individual
    • Perception of the world, expressing emotions, how we treat people

What psychologists do

  • Psychotherapist: does any kind of psychotherapy. Not legally regulated.
  • Psychoanalyst: practice one particular form of therapy — psychoanalysis. Requires degree and training.
  • Psychiatrist: a medical doctor who treats mental disorders.

Steps for critical thinking

  1. Be willing to ask copious “why?” questions
  2. Define your terms (“What makes people happy?” “What does happy mean here?”)
  3. Analyze your own assumptions and biases
  4. Examine the available evidence (and reliability of that evidence)
  5. Weigh the conclusions, generating as many reasonable interpretations of evidence as possible

At the end you arrive at a theory.

Sampling participants for a study

A representative sample is more important than a large sample size.

Descriptive studies

Allow researchers to describe or predict human behavior, but not to explain it.

  • Case studies
    • We can’t deprive children and study the effects, but there are historical cases that can be studied.
    • We often don’t know much about the circumstances, so they’re good for forming hypotheses but not testing them.
  • Observational studies
    • Naturalistic observation: observing people in the natural environment.
    • Laboratory observation: observing people in a lab.
      • More control over the environment.
      • People may act differently because they’re being studied.
  • Psychological tests
    • It’s difficult to make tests that are reliable (producing same results repeatedly) and valid (measuring what they’re supposed to measure).
      • Validity is often measured by the test’s ability to predict other independent ways of measuring the trait (criteria).
  • Surveys
    • Produce lots of data, but really difficult to ask the right questions and get well-sampled and honest data.
    • Changing the phrasing of questions can change the answers.

Correlational studies

To determine whether two or more phenomena are related (and how strongly).

Positive correlation: high values of one correlate with high values of another.

Negative correlation: high values of one correlate with low values of another.

Correlation coefficient: +1 is positive correlation, -1 is negative correlation, 0 is no correlation.

Correlation does not imply causation. Try to find other possible explanations.

  • An illusory correlation is a correlation that is a coincidence.


  • Independent and dependent variables
  • Hold other factors constant
  • Experimental group and control group should have similar people
    • This can be achieved with random assignment if the sample is large

Cross-section study: comparing different age groups.

Longitudinal study: comparing the same people over time.

  • Cross-section studies may conclude that old people perform badly on tests, while longitudinal studies conclude that old people perform about the same.
    • Why? Because young people may be more educated or more familiar with the tests used.

Single-blind studies are where the participant doesn’t know which group they’re in.

Double-blind studies are where the participant and the researcher both don’t know.