The Science of Psychology: Chapter 2 Summary

Psychology's Scientific Method

  • Step 1 - Observing Some Phenomenon
  • Step 2 - Formulating Hypotheses and Predictions
  • Step 3 - Testing Through Empirical Research
  • Step 4 - Drawing Conclusions
  • Step 5 - Evaluating the Theory

The Scientific Method

Types of Psychological Research

  • Descriptive Reasearch - Research that determines the basic dimensions of a phenomenon, defining what it is, how often it occurs, and so on.
  • Correlation Research - Research that examines the relationships between variables, whose purpose is to examine whether and how two variables change together.
  • Experimental Research - Determines whether a casual relationship exists between variables.

Research Samples and Settings

  • Research sample - The subset of the population chosen by the investigator for study.

  • Random Sample - A sample that gives every member of the population an equal chance of being selected.

  • Naturalistic Observation - The observation of behavior in a real-world setting.

  • Population - The entire group about which the investigator wants to to draw conclusions.

Analyzing and Interpreting Data

  • Descriptive Statistics - Mathematical procedures that are used to describe and summarize sets of data in a meaningful way.
  • Measures of central tendency - a single number that indicates the overall characteristics of a set of data. (mean, median, mode)
  • Measures of Dispersion - describes how much the scores in a sample differ from one another. (range - difference between the highest and lowest scores), (standard deviation - tells how much scores in a sample differ from the mean of the sample.)
  • Inferential Statistics - Mathematical methods that are used to indicate whether results for a sample are likely to generalize to a population.

Conducting Ethical Research

Ethic guidelines
  • Informed consent - participants must know what they're doing.
  • Confidentiality - researchers must keep data confidential.
  • Debriefing - researchers must inform the participants about the purpose and methods of the study.
  • Deception - whether or not researchers should inform the participants about everything in the study.

Ethical Experimentation

Thinking Critically about Psychological Research

  1. Avoid over-generalizing based on little information
  2. Distinguish between group results and individual needs
  3. Look for answers beyond a single study
  4. Avoid attributing causes where none have been found
  5. Consider the source of psychological information

The Science of Psychology: Chapter 2 Review Questions


1. What is Psychology's scientific method? (Hint: there are 5 steps.)

2. Why do researchers use random assignment?

3. What is a double-blind study?

4. Name the 3 most common types of experiments that Psychologist use to perform research?

5. What is a placebo and a placebo effect?


1. Observing some phenomenon, Formulating hypothese and predictions, Testing through empirical research, Drawing conclusions, and Evaluating the theory.

2. Researchers assignment of participants to groups by chance, to reduce the likelihood that an experiment's results will be due to preexisting differences between groups

3. An experimental design in which neither experimenter nor the participants are aware of which participants are in the experimental group, and which are in the control group until the results are calculated.

4. Descriptive Research, Correlational Research, and Experimental Research.

5. A placebo is a harmless substance that has no physical or psychological effect on the participant in the experiment. A placebo effect occurs when participants expectations, rather than the experimental treatment, produce an outcome.


The Science of Psychology: Chapter 2 Online Content

Stanley Milgram - Experiment on Obedience Part 1 of 3

Stanley Milgram - Experiment on Obedience Part 2 of 3

Stanley Milgram - Experiment on Obedience Part 3 of 3

The Stanford Prison Experiment