Unit 1: Scientific Foundations of Psychology

AP Psychology: 66 practice questions with detailed explanations.

Unit Study Guide

Executive Summary

Unit 1 supplies the toolkit: how psychologists ask questions, test hypotheses, and know whether results are real. Every later unit assumes these methods.

Schools and perspectives

Psychology's roots run from Wundt's structuralism through functionalism, behaviorism (Watson, Skinner), psychoanalysis (Freud), and humanism (Maslow, Rogers). Modern perspectives — cognitive, biological, evolutionary, sociocultural — each explain behavior through a different lens; no single one is complete.

Research methods

Experiments manipulate an independent variable and measure a dependent variable, with random assignment letting researchers infer causation. Correlational studies measure relationships without manipulation — correlation is not causation. Case studies, surveys, and naturalistic observation describe but cannot establish cause.

Statistics

Descriptive statistics summarize data: mean, median, mode, range, standard deviation. Inferential statistics (p-values) tell whether results could occur by chance; p < .05 is the conventional threshold. A normal distribution is bell-shaped; skewed distributions lean.

Ethics

Informed consent, confidentiality, debriefing, and freedom from harm guide research. Institutional Review Boards (IRBs) approve human studies. Milgram's obedience study (1965: 65% administered maximum shocks) and the Tuskegee syphilis study drove today's strict ethical standards.

Exam traps

Correlation ≠ causation — a third variable can drive both. Random assignment, not random sampling, is what enables causal claims. Statistical significance does not equal practical importance.

Top 5 Concepts to Master

1Identify IV, DV, and confounds in an experiment.
2Decide when a design supports causal vs correlational claims.
3Compute and compare descriptive statistics.
4Apply ethical principles (consent, debriefing, IRB) to studies.
5Spot hindsight and confirmation bias in interpretations.

Key Terms & Definitions

Practice with Flashcards

Hypothesis

Testable prediction about the relationship between variables.

Independent variable

Factor the experimenter manipulates.

Dependent variable

Measured outcome expected to change.

Confounding variable

Uncontrolled factor that could explain results.

Random assignment

Placing participants into conditions by chance.

Correlation coefficient

Statistic (−1 to +1) measuring relationship strength/direction.

Operational definition

Precise, measurable description of a variable.

Mean

Arithmetic average of scores.

Median

Middle score when data are ordered.

Standard deviation

Measure of how spread out scores are.

Statistical significance

Result unlikely to have occurred by chance (p < .05).

Informed consent

Participants agree knowing the study's nature.

Debriefing

Post-study explanation of purpose and any deception.

Confirmation bias

Seeking evidence that supports existing beliefs.

Common Misconceptions: Exam Traps

Correlation proves causation.

Correct: Correlation shows association only; only controlled experiments with random assignment support causal claims.

A statistically significant result is always important.

Correct: Significance concerns probability, not size; tiny effects can be significant in huge samples.

Psychology is just common sense.

Correct: Controlled research regularly overturns intuition — hindsight bias makes findings look obvious afterward.

Random sampling is what allows causal conclusions.

Correct: Random ASSIGNMENT to conditions enables causal inference; sampling concerns generalizability.

Case studies prove general laws.

Correct: Case studies richly describe one subject but cannot establish cause or generalize.

Question Bank Breakdown

By difficulty

easy 25medium 25hard 16

By topic

Statistical Analysis 14Research Methods 11The Experimental Method 9Ethics in Psychology 9Correlational Research 5Introducing Psychology 5