Terms and Concepts to Remember (Psychology Research Methods)
Hindsight bias
- Definition: The tendency to perceive events as having been predictable after they have happened.
- Significance: Distorts memory and judgment; leads to overconfidence in predicting the past; can bias retrospective evaluation of decisions.
- Examples: After a sports game, fans claim they knew the outcome all along; after a stock move, observers retroactively assert they anticipated the result.
- Implications for research and critical thinking: Must be controlled for when evaluating explanations of past events; encourages use of probabilistic thinking and evidence-based reasoning.
Critical thinking and foundational concepts
- Critical thinking
- Definition: The objective analysis and evaluation of information to form a judgment; involves skepticism, evidence weighing, and avoidance of biases.
- Components: clarity, accuracy, relevance, evidence, bias detection, alternative explanations, and logical reasoning.
- Theory
- Definition: A well-substantiated explanation of some aspect of the natural world that can generate testable hypotheses.
- Significance: Guides research, organizes knowledge, and makes predictions.
- Hypothesis
- Definition: A testable prediction derived from a theory.
- Relationship to operational definition: An operational definition specifies exactly how a variable is measured or manipulated so the hypothesis can be tested.
- Operational definition
- Definition: A precise, unambiguous description of how a variable will be measured or manipulated in a study.
- Purpose: Ensures replicability and clear interpretation of results.
- Replication
- Definition: Repeating a study to verify whether results hold under different samples and conditions.
- Importance: Establishes reliability and generalizability of findings.
Research methods and data collection
- Case study
- In-depth analysis of a single person or a small number of individuals.
- Pros: rich, detailed information; useful for exploring rare phenomena.
- Cons: limited generalizability; potential for researcher bias.
- Survey
- Definition: A method of gathering self-reported data from a sample.
- Considerations: question wording, sampling method, anonymity, response bias.
- Population
- Definition: The entire group about which information is desired.
- Random sample
- Definition: A sample in which each member of the population has an equal chance of being selected.
- Purpose: Helps ensure representativeness and generalizability.
- Naturalistic observation
- Definition: Observing subjects in their natural environment without manipulation.
- Pros: high ecological validity; minimal interference.
- Cons: less control over variables; observer effects possible.
- Correlation
- Definition: A statistical measure of how two variables co-vary; does not imply causation.
- Direction: positive, negative, or zero association.
- Limitation: cannot establish cause-effect relationships.
- Correlation coefficient
- Definition: A numeric index of the strength and direction of a linear relationship between two variables.
- Formula (population sample):
- r = \frac{\text{cov}(X,Y)}{sX sY} = \frac{\sum{i=1}^n (xi - \bar{x})(yi - \bar{y})}{\sqrt{\sum{i=1}^n (xi - \bar{x})^2} \sqrt{\sum{i=1}^n (y_i - \bar{y})^2}}
- Interpretation: r ranges from -1 to 1; values near ±1 indicate strong linear relationships; values near 0 indicate weak linear relationships.
- Scatterplot
- Definition: A graph of paired data points illustrating the relationship between two quantitative variables.
- Use: Visual assessment of direction, form, and strength of a relationship; helps identify outliers.
- Illusory correlation
- Definition: Perceiving a relationship between variables even when none exists or when the association is weak.
- Causes: selective attention, confirmation bias, and sensational or memorable anecdotes.
Experimental design and variables
- Experiment
- Definition: A study in which researchers manipulate one or more independent variables and observe effects on dependent variables, while controlling extraneous variables.
- Random assignment
- Definition: Randomly assigning participants to experimental conditions to minimize preexisting differences between groups.
- Purpose: Supports internal validity and causal inference.
- Double-blind procedure
- Definition: A research design in which neither participants nor experimenters know who is in the experimental or control group.
- Purpose: Reduces bias in treatment administration and assessment of outcomes.
- Placebo effect
- Definition: Participants experience a perceived or actual improvement due to their expectations, not the treatment itself.
- Implication: Must be controlled with placebo controls and blinding when possible.
- Experimental group
- Definition: The group that receives the treatment or manipulation of the independent variable.
- Control group
- Definition: The group that does not receive the experimental manipulation or receives a neutral/placebo condition.
- Independent variable
- Definition: The manipulated variable hypothesized to affect the dependent variable; the cause in the experiment.
- Confounding variable
- Definition: An extraneous variable that correlates with both the independent and dependent variables, potentially biasing results.
- Example: In a drug study, participants’ age could confound the effect if not controlled.
- Dependent variable
- Definition: The outcome measured in the study; the effect in the experiment.
Descriptive statistics and data distributions
- Mode
- Definition: The value that occurs most frequently in a data set.
- Mean
- Definition: The arithmetic average of the data.
- Formula: \bar{x} = \frac{1}{n} \sum{i=1}^{n} xi
- Median
- Definition: The middle value when data are ordered; for even n, the average of the two central numbers.
- Range
- Definition: The difference between the maximum and minimum values: \text{Range} = x{(n)} - x{(1)}
- Standard deviation
- Definition: A measure of the amount of variation or dispersion in a set of values.
- Formula (sample): s = \sqrt{\frac{1}{n-1} \sum{i=1}^n (xi - \bar{x})^2}
- Normal curve (normal distribution)
- Definition: A symmetric, bell-shaped distribution where mean = median = mode in the population.
- Properties: 68-95-99.7 rule; in standard form, the probability density is given by
- f(x) = \frac{1}{\sigma \sqrt{2\pi}} \exp\left(-\frac{(x - \mu)^2}{2\sigma^2}\right)
- Statistical significance
- Definition: A determination that observed results are unlikely under the null hypothesis.
- p-value: Probability of obtaining results at least as extreme as observed if the null hypothesis is true.
- Decision rule: Reject H0 if p < \alpha, with common alpha = 0.05 (i.e., \alpha = 0.05).
- Note: Statistical significance does not imply practical significance; consider effect size and context.
Culture and ethics in research
- Culture
- Definition: Shared beliefs, norms, values, and practices that shape behavior and interpretation in research contexts.
- Relevance: Affects participant recruitment, interpretation of results, and generalizability across societies.
- Informed consent
- Definition: An ethical requirement whereby participants voluntarily agree to participate after being informed about study purpose, procedures, risks, and benefits.
- Components: voluntary participation, comprehension, and the freedom to withdraw without penalty.
- Debriefing
- Definition: Post-study explanation provided to participants, including the study’s purpose, methods, and any deception used, along with resources or support if needed.
Connections and practical implications
- Linking concepts across methods
- Replication strengthens reliability; replication failures prompt re-evaluation of theory and methods.
- Operational definitions ensure that constructs are measured consistently across studies, aiding replication.
- Random sampling and random assignment enhance external and internal validity, respectively.
- Blinding and placebo controls reduce biases that could inflate treatment effects.
- Real-world relevance
- Understanding bias (hindsight, illusory correlation) helps in evaluating everyday judgments and media reports.
- Statistical literacy (mean, median, mode, standard deviation, correlation, p-values) enables critical interpretation of results in news, policy, and personal decisions.
- Ethical implications
- Informed consent and debriefing protect participants; ethical considerations govern use of deception, data confidentiality, and risk minimization.
- Foundational principles
- The scientific method relies on hypothesis-driven research, operational definitions, controlled experimentation, indexing with descriptive and inferential statistics, and ongoing ethical reflection.
