Research Methods, Designs, Statistics, and Coding in Psychological Science
Intuition vs. Scientific Method
Intuition can be misleading even with high confidence.
Example: Visual illusion of line lengths where intuition is incorrect.
Psychological science uses the scientific method to overcome the limitations of intuition.
Scientific Method:
Observation
Hypothesis
Theory
Design: Structuring studies to test hypotheses. What kind of research design will we use?
Data: Collected (in that research design) to test hypotheses.
Psychological science relies on objective, systematic, and rigorous methodologies.
Standardized procedures ensure understandability, interpretability, replicability, and testability of findings.
Scientific Method Terms and Definitions
Variables: Must be operationally defined.
Hypothesis: A tentative, testable idea based on observations.
Statistical Significance: Determining the likelihood of results occurring by chance using statistical methods.
Variables and Operational Definitions
Operational Definition: Specific way of measuring or manipulating a variable.
Example 1: Research question: Are wealthy people less generous?
Level of Wealth: Measured by asking people how much money they make.
Level of Generosity: Measured by asking people to give points to a stranger in an experiment.
Measured vs. Manipulated Variables
Measured: Variables that are observed and recorded.
Manipulated: Variables that are changed or controlled by the researcher.
Example 2: Intoxication
Measured: Recording blood alcohol content (BAC) in a pub.
Manipulated: Randomly assigning participants to receive either vodka or water in a lab setting, then measuring BAC.
Variables that can only be measured:
Depression: Cannot ethically induce depression in participants.
Gender, race, or ethnicity: Cannot be manipulated.
Replication and Generalizability
Replication: Repeating a research study to increase confidence in findings.
Dissemination: Sharing findings with others.
Increased confidence with more replications.
Generalizability: Repeating a study with a new sample or population.
Example: Behavior of Golden Retriever puppies.
Does it generalize beyond one puppy to a group of puppies?
Does it generalize to all puppies or adult Golden Retrievers?
Does it generalize to all dog breeds?
Scientific Journals and Peer Review
Scientific journals: Where psychological scientists publish research.
Peer-reviewed journals: Articles are evaluated by experts in the field.
Peer review process:
Reviewers identify strengths and weaknesses.
Feedback is given to authors for revision.
Ensures published research is innovative, important, and well-conducted.
The Scientific Method / Theory-Data Cycle
Objective systematic observations of the world are essential.
Hypotheses and theories are tested rather than relying on intuition.
Six basic steps:
Observe a question of interest.
Review existing literature to understand what is already known.
Develop a testable hypothesis.
Design a research study to test the hypothesis.
Collect and analyze data to see if the hypothesis is supported.
Publish research in a peer-reviewed journal.
Revise theory or propose a new one based on findings.
Replicate to test generalizability
Example: Hunger and Exam Performance
Observation: Noticing poorer performance when hungry before an exam.
Hypothesis: Eating a snack before an exam improves performance.
Research Design: Randomly assign students to either have a snack or not before an exam.
Measured variable: Exam performance.
Data Analysis: Use a t-test to compare the two groups.
Publish results, but further studies may be needed.
Further Questions: What type of snack matters?
Develop a theory about hunger and performance in general.
Research Ethics in Psychology
Informed Consent: Participants must read and understand the study's details, risks, benefits, and compensation before agreeing to participate.
Voluntary Participation: Participants must be informed they are participating in a study and can opt-out.
Confidentiality: Participant data must be kept confidential, often using assigned numbers instead of names.
Benefits vs. Risks: The scientific benefits of the research must outweigh the risks to participants.
Limited Deception: Deception should be minimized, and a full debriefing must occur afterward explaining any deception.
Institutional Review Board (IRB) Review: Research proposals are reviewed by professionals and community members to ensure studies are well-designed and ethical.
IRB checks for low risk to participants and high benefit to society.
IRB approves studies to be conducted.