Research Methods in Psychology

Overview

This lecture covers research methods in psychology, including descriptive, correlational, and experimental methods, as well as key design considerations and ethical guidelines.

Descriptive Methods

• Descriptive methods include naturalistic observation, case studies, and surveys.

• Demand characteristics (observer effect) mean people may change behavior when watched.

  Observer bias occurs when researchers' expectations influence observations.

• Single-blind studies hide observation from subjects; double-blind studies hide it from both subjects and researchers.

• Case studies involve in-depth analysis of unique individuals (e.g., patient HM with hippocampus removal).

• Case studies can highlight important insights but may not generalize to the population.

• Surveys collect large amounts of data quickly and cheaply, requiring representative, randomly-selected samples.

• Poorly designed survey questions (e.g., double-barreled, leading, non-specific, overlapping categories) can reduce data quality.

Correlational Methods

• Correlation measures how two naturally occurring variables relate, allowing for predictions.
• Positive correlation: both variables increase or decrease together; negative correlation: one increases as the other decreases.
• Correlations are depicted with scatter plots and measured using the correlation coefficient (ranges from -1 to +1).
• Correlation does not imply causation due to the possible influence of a third variable.
• Example: Toasters and contraception use correlated due to socioeconomic status as a third variable.
• The third variable problem means causal relationships cannot be inferred from correlation.

Experimental Methods

• Experiments allow researchers to manipulate variables to determine cause and effect.
• Key features include random assignment, control groups, and experimental groups.
• Random assignment with matching ensures groups are balanced for key characteristics.
• Independent variable: manipulated by researchers (e.g., breastfeeding vs. formula).
• Dependent variable: measured outcome (e.g., intelligence test score).
• Control group receives no treatment; experimental group receives the treatment.
• Random assignment and matching minimize extraneous variables.

Operational Definitions

• Researchers must define variables in measurable, objective terms (operational definitions).
• Examples: Learning = score ≥80% on final, Aggression = number of physical attacks, Sleep = EEG measurement.

Experimental Designs

• Within-subjects design: each participant experiences all conditions (compares them to themselves).
• Between-subjects design: each participant experiences one condition (compares different groups).
• Mixed-model design: combines within- and between-subjects comparisons.
• Example: A drug study measuring blood pressure before and after treatment in both males and females.

Ethics in Psychological Research

• Ethical research requires IRB approval and following guidelines: informed consent, voluntary participation, no coercion, and confidentiality.
• Deception is allowed only when justified, and participants must be debriefed afterward.

Key Terms & Definitions

• Demand characteristics (Observer effect) — when participants alter behavior because they know they are observed.
• Observer bias — when researchers' expectations influence their observations.
• Single-blind study — only subjects are unaware of the observation or study purpose.
• Double-blind study — both subjects and researchers don't know who receives treatment or the study purpose.
• Correlation coefficient — a statistical measure of the strength/direction of a relationship between variables (ranges -1 to +1).
• Third variable problem — an unaccounted factor that may cause both variables to correlate.
• Operational definition — a precise, measurable definition of how a variable is defined and assessed.
• Random assignment — assigning participants to groups by chance to avoid pre-existing differences.
• Control group — does not receive the treatment.
• Experimental group — receives the manipulated variable.
• Within-subjects design — same subjects experience all conditions.
• Between-subjects design — different subjects assigned to different conditions.

Action Items / Next Steps

• Read the textbook chapter on research methods for further understanding.
• Review examples of survey question design.
• Complete the posted practice exercises on correlation and experimental methods.