Cognitive Dissonance and Experimental Design Principles

Cognitive dissonance

Holding conflicting values and behaviors simultaneously.

Festinger and Carlsmith

Researchers who studied cognitive dissonance effects.

Independent variable (IV)

Variable manipulated by the researcher in experiments.

Dependent variable (DV)

Measured outcome affected by the independent variable.

Control variables

Factors kept constant to prevent influence on results.

Covariance

Relationship between different levels of IV and DV.

Temporal precedence

Causal variable must occur before the outcome variable.

Internal validity

Confidence that results are due to the IV only.

Confound

Alternative explanation that threatens internal validity.

Treatment groups

Participants receiving the experimental treatment in studies.

Control group

Participants not receiving the treatment for comparison.

Placebo group

Control group receiving a non-active treatment.

Design confounds

Variables that systematically vary with the IV.

Selection effects

Differences in participant types across IV levels.

Van Kleef et al. (2012)

Study on serving bowl size and consumption.

Large bowl session

Experimental condition with larger serving bowls.

Medium bowl session

Experimental condition with smaller serving bowls.

Systematic variability

Consistent differences affecting study outcomes.

Unsystematic variability

Random differences not affecting study outcomes.

Self-report responses

Participants' subjective feedback on their experiences.

Behavioral responses

Observable actions measured during the study.

Physiological responses

Biological measures indicating participant reactions.

Liking ratings

Participants' evaluations of task enjoyment on a scale.

Insufficient justification

Lack of adequate reason leading to attitude change.

Treatment-as-usual

Standard care provided without experimental intervention.

Selection effects

Bias from non-random participant group assignments.

Random assignment

Participants sorted randomly into study groups.

Randomized block design

Participants grouped by characteristics before random assignment.

Matched groups

Participants paired by shared characteristics for comparison.

Independent-groups design

Different groups experience different levels of the IV.

Posttest-only design

Participants tested on DV after IV exposure.

Pretest/posttest design

Participants tested on DV before and after IV.

Within-groups design

Same participants tested across all IV levels.

Repeated-measures design

Participants measured multiple times after IV exposure.

Concurrent-measures design

Participants exposed to all IV levels simultaneously.

Construct validity

Degree to which manipulations accurately reflect concepts.

Manipulation check

Assessment to verify effectiveness of experimental manipulation.

Pilot study

Preliminary study to test feasibility and design.

Power

Study's ability to detect true effects.

Effect-to-error ratio

Comparison of signal strength to background noise.

Cognitive tasks

Activities requiring mental processes for assessment.

Shared experience

Experience involving multiple participants simultaneously.

Chocolate study

Research on enjoyment from shared versus solo experiences.

Eager/motivated parents

Parental enthusiasm influencing treatment group selection.

Unsystematic variability

Random differences affecting study outcomes.

Misery loves company

Emotional distress often seeks shared experiences.

External validity

Generalizability of causal relationships across contexts.

Random sampling

Selection method for external validity enhancement.

Random assignment

Method ensuring internal validity in experiments.

Internal validity

Degree to which causal conclusions are justified.

Statistical validity

Data support for the causal claim made.

Effect size

Magnitude of difference or relationship strength.

Cohen's d

Standardized measure of effect size.

Confidence intervals

Range estimating population difference likelihood.

Statistical significance

Probability that observed difference is not due to chance.

Design confounds

Extraneous variables affecting internal validity.

Selection effects

Bias from non-random assignment in groups.

Order effects

Influence of sequence on within-group responses.

Null hypothesis

Assumes no effect or difference exists.

Alternative hypothesis

Claims a significant effect or difference exists.

Research hypothesis

Researcher's expected outcome based on theory.

Sampling error

Random variability affecting group differences.

Homogeneous samples

Similar participant characteristics reducing variability.

Big bowl effect

Larger serving vessels increase food consumption.

Wansink (2006) study

Research supporting larger bowl consumption findings.

Hypothesis testing

Process of evaluating assumptions through research.