Unit 1 - Psychology Research Methods and Biases

Overconfidence Bias

Tendency to think you know more than you do or are better at something than you are.

Hindsight Bias

Tendency to believe, after learning the outcome, that you knew it all along; often called Monday Morning Quarterbacking.

Barnum Effect

Tendency to accept very general or vague characterizations of oneself as accurate.

Confirmation Bias

Tendency to interpret new evidence as confirmation of one’s existing beliefs or theories.

Experimental Method

Research approach that manipulates an independent variable to observe its effect on a dependent variable; often uses random assignment and control groups.

Non-Experimental Method

Research approaches that do not manipulate the independent variable (e.g., case studies, naturalistic observation, surveys, correlations, meta-analyses).

Independent Variable (IV)

The variable that the experimenter manipulates; the presumed cause.

Dependent Variable (DV)

The variable measured in an experiment; the presumed effect.

Random Assignment

Assigning participants to experimental and control groups by chance to reduce bias.

Experimental Group

Group exposed to the independent variable.

Control Group

Group not exposed to the independent variable.

Double-Blind Procedure

Neither participants nor researchers know the expected outcome to prevent bias.

Single-Blind Procedure

Participants are unaware of the expected outcome, but researchers may know.

Placebo Effect

Behavioral change due to expectations rather than the actual treatment.

Hawthorne Effect

Alteration of behavior by subjects due to awareness of being observed.

Demand Characteristics

Cues that may indicate the research objectives and influence participant behavior.

Random Sampling

Selecting a sample so that every member of the population has an equal chance of inclusion.

Convenience Sampling

Sampling based on availability, which can lead to biased results.

Sampling Bias

Flawed sampling that produces unrepresentative data.

Naturalistic Observation

Watching subjects in their natural environment without manipulating the environment.

Case Study

In-depth study of a single person, group, or situation over time; rich data but limited generalizability.

Survey Method

Gathers self-reported attitudes or behaviors, often via representative random samples.

Social Desirability Bias

Respondents give answers they think will look good, concealing true opinions.

Wording Effect

How question wording influences respondents’ answers.

Informed Consent

Ethical requirement to inform participants and obtain voluntary participation.

Confidentiality

Protecting participants' data from disclosure.

Debriefing

Providing participants with a full explanation after participation in a study.

Ethics in Animal Research

Clear purpose, humane treatment, legal acquisition, and minimizing suffering.

Ethics in Human Research

Informed consent, protection from harm, confidentiality, and debriefing.

Theory

An explanation that organizes observations and predicts outcomes.

Scientific Method

Systematic observation, measurement, experiment, and the formulation, testing, and modification of hypotheses.

Applied Research

Research with clear, practical applications intended to solve real-world problems.

Basic Research

Research aimed at growing general knowledge, not necessarily with immediate applications.

Experimental Hypothesis

A statement predicting that the independent variable will affect the dependent variable.

Null Hypothesis

A statement that there is no effect or relationship between variables.

Replication

Repeating a study to see if findings hold with different participants and conditions.

Descriptive Research

Research that aims to observe and describe behavior (case studies, surveys, naturalistic observation).

Correlational Research

Research to detect naturally occurring relationships between variables; cannot establish causation.

Experimental Research

Research that manipulates variables to determine cause-and-effect relationships.

Third Variable Problem

A correlation may be due to a third variable influencing both variables.

Directionality Problem

Uncertainty about which variable affects the other.

Positive Correlation

Variables move in the same direction (both increase or both decrease).

Negative Correlation

Variables move in opposite directions (one increases as the other decreases).

Correlation Coefficient (r)

A number from -1 to +1 that measures the strength and direction of a linear relationship.

Illusory Correlation

Perceiving a relationship between two variables when none exists; often due to memorable events or selective attention.

Recency Bias

Tendency to rely on the most recently received information when forming judgments.

Regression to the Mean

Extreme scores tend to move toward the average on subsequent measurements.

Statistical Significance

Probability that observed results are due to chance; p-value < .05 is commonly used threshold.

p-value

Probability of obtaining results at least as extreme as observed, assuming the null hypothesis is true.

Effect Size

The magnitude of a relationship or difference, indicating practical significance.

Qualitative Research

Research relying on non-numerical data (interviews, observations, narratives).

Quantitative Research

Research relying on numerical data and statistical analysis.

Meta-Analysis

Statistical synthesis that combines results from multiple studies.

Normal Distribution

Bell-shaped, symmetrical distribution where mean = median = mode; about 68% within ±1 SD.

Skewness

Asymmetry in a distribution caused by outliers; positive skew has more low scores, negative skew has more high scores.

Outliers

Scores that are far from the rest of the data and can distort distributions.

Range

Difference between the highest and lowest scores.

Standard Deviation

Average distance of scores from the mean; measures data spread.

Mean

Arithmetic average of a set of numbers.

Median

Middle value when data are ordered.

Mode

Most frequently occurring value in a data set.

Percentile Rank

Percentage of scores that fall below a given score.