Research Methods in Psychology: Constructs, Validity, and Ethical Practices

Theory

An organized explanation of behavior or events that helps researchers explain and predict behavior and develop research questions and hypotheses.

Why is theory crucial in research?

Theory provides a framework for explaining and predicting behavior and guides researchers in developing research questions and hypotheses.

Construct

An abstract concept or idea that researchers want to study, such as anxiety, intelligence, happiness, or addiction.

Operational definition

The specific, measurable way a researcher defines and measures a construct in a study.

Construct vs. operational definition

Construct = what you are studying. Operational definition = exactly how you measure it.

Example of an operational definition for addiction

Addiction could be measured by the number of days per month a person uses an addictive substance.

Example of an operational definition for hot weather

Hot weather could be measured by the daily temperature in degrees Fahrenheit.

Example of an operational definition for violent crime

Violent crime could be measured by the number of violent crimes reported to police each day.

Example of an operational definition for social anxiety

Social anxiety could be measured using a participant's score on a standardized social anxiety questionnaire.

Example of an operational definition for therapy being helpful

Therapy could be considered helpful if participants' social anxiety questionnaire scores decrease after treatment.

Why are operational definitions important?

They make abstract constructs measurable, provide clarity, and allow other researchers to replicate the study.

Deception

Intentionally withholding or misleading participants about some aspect of a research study.

When is deception permissible?

Deception may be used when it is necessary for the research, there is no reasonable alternative, the study has important scientific value, and participants are not exposed to unnecessary harm.

Debriefing

Explaining the true purpose and procedures of a study to participants after they participate.

Goals of debriefing

To explain the study, reveal any deception, answer participants' questions, and help protect participants from possible negative effects of the research.

Informed consent

A process in which participants are given enough information about a study to voluntarily decide whether to participate.

Why is informed consent important?

It respects participants' autonomy and ensures that participation is voluntary and informed.

Confidentiality

When the researcher knows participants' identities but protects their personal information from being revealed.

Anonymity

When participants' identities are not known or cannot be connected to their individual responses.

Confidentiality vs. anonymity

Confidentiality = the researcher knows who you are but protects your information. Anonymity = your identity is not known or cannot be linked to your responses.

Three major ethical issues

Informed consent, confidentiality, and protection from harm are major ethical concerns. Deception and the right to withdraw are also important.

Why is reading past research important?

It helps researchers understand what is already known, identify gaps, avoid unnecessary repetition, develop research questions, and build on previous findings.

Good research question

A question that is clear, specific, focused, researchable, measurable, answerable with evidence, and ethical.

Internal validity

The degree to which researchers can confidently conclude that the independent variable caused changes in the dependent variable.

External validity

The degree to which research findings can be generalized to other people, settings, or situations.

Internal vs. external validity

Internal validity asks, "Did X really cause Y?" External validity asks, "Can these findings apply outside this study?"

How can a study have strong internal validity?

By using random assignment, controlling variables, standardizing procedures, and eliminating alternative explanations.

How can a study have strong external validity?

By using participants who represent the population of interest and conducting research in realistic settings.

Causation

Causation means that a change in one variable directly produces a change in another variable.

Three requirements for causation

Covariation, temporal precedence, and ruling out plausible alternative explanations.

Covariation

The cause and effect variables must be related or change together.

Temporal precedence

The proposed cause must occur before the proposed effect.

Alternative explanations

Researchers must rule out other variables that could explain the relationship between the variables.

Correlation

When two variables are related or associated with each other.

Correlation does not equal causation

A correlation shows a relationship but does not prove that one variable caused the other.

Experimental research and causation

Experiments can establish causation because researchers manipulate the IV, measure the DV, and control potential confounding variables.

Survey research and causation

Survey research can show relationships between variables but cannot establish causation by itself.

Psychological research is probabilistic

Research describes patterns and probabilities rather than guaranteeing that an outcome will happen for every individual.

Why is psychological research probabilistic?

Human behavior is influenced by many factors, so research findings usually describe what is likely to happen rather than what will always happen.

Confounding variable

An unwanted variable that provides an alternative explanation for the results of a study.

How do confounding variables threaten internal validity?

They make it unclear whether the independent variable or another variable caused the observed results.

How can confounding variables be avoided?

Use random assignment, hold important factors constant, standardize procedures, and control other variables.

Independent variable (IV)

The variable that the researcher manipulates or changes.

Dependent variable (DV)

The variable that the researcher measures to see whether it changes as a result of the IV.

Levels

The different conditions or groups of the independent variable.

Background music experiment: IV

The type of background music.

Background music experiment: levels

Classical music and complete silence.

Background music experiment: DV

Test performance.

Background music experiment: operational definition of DV

The participant's score on the math test.

Background music experiment: possible controls

The same math test, same instructions, same testing environment, and same amount of time.

Caffeine and reaction time: correlation of r = -.81

A strong negative correlation, meaning higher caffeine levels are associated with faster reaction times, but the correlation alone does not prove causation.

Caffeine experiment: IV

Caffeine.

Caffeine experiment: levels

Caffeine and no caffeine/placebo.

Caffeine experiment: DV

Reaction time.

Caffeine experiment: operational definition of reaction time

The number of milliseconds it takes a participant to respond to a visual stimulus on a computer reaction-time test.

Caffeine experiment: experimental hypothesis

Participants who receive caffeine will have faster reaction times than participants who do not receive caffeine.

Caffeine experiment: possible controls

The same reaction-time test, same testing environment, same instructions, and same amount of testing time.

Unemployment and alcohol study: major problem

The researcher cannot conclude that unemployment causes increased alcohol consumption because the study was correlational rather than experimental.

Unemployment and alcohol study: possible confounds

Financial stress, relationship problems, existing drinking habits, mental health, or other factors could influence alcohol consumption and unemployment.

Unemployment and alcohol study: another problem

Only 50% of the surveys were returned, so the people who responded may differ from those who did not respond.

Pregnancy optimism study: major problem

The researchers found a relationship but cannot conclude that optimism caused healthier babies without ruling out alternative explanations.

Possible alternative explanations in pregnancy study

Exercise, nutrition, stress, access to healthcare, income, or other lifestyle and health factors could influence the results.

How to recognize a causal claim

Look for language such as "causes," "produces," "leads to," or "results in." Ask whether the study was actually an experiment.

How to recognize a correlational claim

Look for words such as "related to," "associated with," "correlated with," or "linked to."

Key rule for research methods

CORRELATION ≠ CAUSATION.

Experiment

Research in which the researcher manipulates an independent variable and measures its effect on a dependent variable.

Random assignment

Randomly placing participants into different experimental groups to help make the groups similar and reduce confounding variables.

Control variable

A factor that researchers keep the same across groups so it does not become a confounding variable.

Research hypothesis

A specific prediction about the relationship between variables or the expected outcome of a study.