Lecture 2 The Science of Psychology

Today’s Outline Critical Thinking & Science Psychological Methods Types of data Self report Observation Research Design Archival Correlational Longitudinal Experimental

Methods of Psychology: Scientific Method Science starts with an attitude and a desire for the truth Systematic empirical study of phenomena __________: keep the bias out, include all data and information even if it doesn’t “fit” __________: based on observable events __________: must be measurable

Short Video What was the study? Did people believe it? What’s a placebo? Why do placebos work?

Problems with Common Sense People see some parts of the world and miss others due to preconceptions, ability, attention, etc.) People notice those things that fit preconceptions People often believe to be true whatever feels good

The Scientific Method To develop theories about the world and to test those theories using observations Theory: An explanation Scientific theory is backed by data The scientific process Is self correcting (theories are tested, then revised, then tested) Theories are _________ The process is objective and public

The Science of Psychology Separating anecdotes, folk wisdom and advice from data and conclusions! Scientific Research is… Formulating _______________ Testing __________ using the scientific method Interpreting the results Communicating the results --- realistically

The goals of science Description: What happens? Prediction: When does it happen? Explanation: Why does it happen? Theory Causal Inferences Intervention/Application: What could be done to help? These all build on each other

Self Report Self-report methods: ask participants to tell you Interviews Questionnaires Daily diary methods

Observational Data Observational Data Observations in natural settings Laboratory-based observation

Research Designs Archival – digging through the vaults… Correlational research – when one goes up, what happens to the other? Longitudinal research – how do things relate over time? Experimental research – if one is changed, what happens to the other?

Archival Research Researchers examine existing data that may or may not have been intended for research Harker and Keltner (2001) used yearbook pictures to predict marital outcomes 30 years later

Archival Results Smiling at age 20 predicted:

Correlational Research Assess the naturally occurring associations among two variables Positive correlation rewards are positively associated with satisfaction Negative correlation conflicts are negatively associated with satisfaction

Correlational research The statistical concept of a “correlation coefficient (r)” Perfect positive correlation (+1.00) No relationship (0.00) Perfect negative correlation (-1.00)

Correlation does not imply causation! Three possible interpretations of any correlation

Pros and Cons of Correlational Research (descriptive) Advantages Disadvantages

Longitudinal Research Data collected at 2 or more time points Associations among variables across time How are feelings of love across time associated with divorce?

Longitudinal Research Associations among variables within a day How does a partner’s behavior during the day influence feelings of commitment at night?

Pros and Cons of Longitudinal Advantages Disadvantages

Experimental Research Manipulate one variable to see if it causes changes in another variable. Does arousal lead to greater liking? A B

Testing the WHATs and WHYs 1:1 correspondence If you pour x into y, you know x caused the explosion If you pour x and z into y, you don’t know what caused the explosion Random Assignment In large enough samples, characteristics will be equally distributed

Experimental: Video Games & Violence What is an independent variable? What is a dependent variable? What is the point of experiments? What is random assignment? How are differences controlled?

Pros and Cons of Experimental Advantages Disadvantages