AP Psychology Unit 0 Notes: Science Practices

Jumpstart your test prep with our free AP Psychology study notes, recently updated for the 2025 AP Psychology exam. These AP Psychology study notes should be used to supplement what you’re learning in your AP Psych class. You will find the content from this unit in the textbook you use in your AP Psychology class in the history and research methods chapters.

Please note that these free AP Psychology study notes follow the units in the 2025 Barron's AP Psychology Premium Prep book:

• AP Psychology Unit 0: Science Practices Notes
• AP Psychology Unit 1: Biological Basis of Behavior Notes
• AP Psychology Unit 2: Cognition Notes
• AP Psychology Unit 3: Development and Learning Notes
• AP Psychology Unit 4: Social Psychology, Personality, Motivation, and Emotion Notes
• AP Psychology Unit 5: Mental and Physical Health Notes

More study strategies and expert tips can be found in our latest AP Psychology prep book.

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AP Psychology: The 8 Psychological Perspectives 

The contemporary psychological perspectives can be placed into eight categories. Ahead of the AP exam, be sure to review these psychological perspectives:

1. Humanist Perspective
2. Psychodynamic Perspective
3. Biopsychology (or Neuroscience) Perspective
4. Evolutionary (or Darwinian) Perspective
5. Behavioral Perspective
6. Cognitive Perspective
7. Social-Cultural (or Sociocultural) Perspective
8. Biopsychosocial Perspective

AP Psychology: Unit 0 Key Terms

Below, we describe some of the key terms you should review ahead of the AP Psychology exam.

• Hindsight bias: People have the tendency upon hearing about research findings (and many other things) to think that they knew it all along; this tendency is called hindsight bias.
• Confirmation bias: Confirmation bias is the tendency to pay more attention to information that supports our preexisting ideas.
• Hypothesis: A hypothesis expresses a relationship between two variables. Variables, by definition, are things that can vary among the participants in the research.
• Sample: The group of individuals on which the research will be conducted.
• Confounding variable: A confounding variable is any difference between the experimental and control conditions, except for the independent variable, that might affect the dependent variable.
• Experimenter bias: Experimenter bias is a special kind of situation-relevant confounding variable. Experimenter bias is the unconscious tendency for researchers to treat members of the experimental and control groups differently to increase the chance of confirming the researchers' hypothesis.
• Double-blind study: A double-blind study occurs when neither the participants nor the researcher are able to affect the outcome of the research.
• Positive correlation: A positive correlation between two things means that the presence of one thing predicts the presence of the other.
• Negative correlation: A negative correlation means that the presence of one thing predicts the absence of the other.
• Naturalistic observation: Sometimes researchers opt to observe their participants in their natural habitats without interacting with them at all. Such unobtrusive observation is called naturalistic observation. The goal of naturalistic observation is to get a realistic and rich picture of the participants’ behavior. To that end, control is sacrificed.
• Case study: The case study method is used to get a full, detailed picture of one participant or a small group of participants.
• Central tendency: Measures of central tendency attempt to mark the center of a distribution. Three common measures of central tendency are the mean, median, and mode.
• Correlation: A correlation measures the relationship between two variables.
• Peer review: Prior to publication, psychology studies undergo peer review, a process by which a paper is read by several others in the field and the is author asked to make revisions in order to ensure high quality publications.
• Informed consent: Participants must know that they are involved in research and give their consent.
• Debriefing: After the study, participants should be told the purpose of the study and provided with ways to contact the researchers about the results. 

APA Ethical Guidelines

Ethical considerations are a major component in research design. You should know and understand the ethical guidelines established by the APA (American Psychological Association) for human and animal research and be prepared to apply the concepts to specific research designs.