Using the scientific method Psych 231: Research Methods in Psychology

Lab Announcements Library Labs: Milner rooms 164d (for the psycINFO lecture) North East classroom 3rd floor (to meet with the GAs) Next week’s labs: Download and read the Assefi & Garry (2003) article before labs

Reading a research article Going to hold off and talk about this in the next lecture when discussing APA style

Conducting Research: An example Claim: People perform best with a good night of sleep. How might we go about trying to test this claim? What are the things (variables) of interest? What is the hypothesized relationship between these variables? How should we test it? How do we observe the behavior? What research design should we use?

General research approaches Observational approaches: How do we observe the behaviors of interest? Naturalistic observation Participant observation Survey & interviews Archival data Systematic (contrived) observation

Observational Methods Naturalistic Observation: Observation and description of behaviors within a natural setting Jane Goodall Dian Fossey Good for behaviors that don’t occur (as well) in more controlled settings Often a first step in the research project Can be difficult to do well

Observational Methods Participant Observation: The researcher engages in the same behaviors as those being observed May allow observation of behaviors not normally accessible to outside observation Internal perspective from direct participation But could lead to loss of objectivity Potential for contamination by observer

Observational Methods Survey methods: Questionnaires and interviews that ask people to provide information about themselves Widely used methodology Best way to collect some kinds of information: Descriptive, behavioral, and preferential e.g., demographic information, recreational behavior, and attitudes Large amounts of data can be collected quickly with relatively little cost (effort, time, etc.) But they’re often not as “cheap” as you may think Done correctly, can be a very difficult method

Archival data: Rather than making direct observations, researcher examines existing public or private records If the appropriate existing records can be found, no need for data collection Data set may be more extensive than what you could collect yourself However, you are limited to the data that exists, may be no way to collect follow-up data Data may be of observations that you cannot (ethically) collect or manipulate E.g., murder rates, who marries whom, etc. Word of caution: be aware of how and where the data were collected Observational Methods

Observation without manipulation Advantages Complex patterns of behavior in particular settings Useful when little is known about the subject of study May learn about something that never would have thought of looking at experimentally Disadvantages Causality is a problem Threats to internal validity because of lack of control Every confound is a threat Lots of alternative explanations Directionality of the relationship isn’t known Sometimes the results are not reproducible

Observational Methods Systematic (Contrived Observation): The observer sets up the situation that is observed Observations of one or more specific variables made in a precisely defined setting Much less global than naturalistic observations Often takes less time However, since it isn’t a natural setting, the behavior may be changed

General research approaches Case studies Intensive study of a small set of individuals and their behaviors Correlational Looking for a co-occurrence relationship between two (or more) variables Quasi-experimental Experimental designs with one or more non-random variables Experimental Investigating the cause-and-effect relationship between two (or more) variables through the manipulation of variables

Descriptive: Case Histories This view has a number of disadvantages There may be poor generalizabilty There are typically a number of possible confounds and alternative explanations Intensive study of a single person, a very traditional method Typically an interesting (and often rare) case Phineas Gage Sept 13, 1848 Explosion propelled a railroad tamping rod through his brain

Correlational Methods Measure two (or more) variables for each individual to see if the variables co-occur (suggesting that they are related) Used for: Predictions Reliability and Validity Evaluating theories Problems: Can’t make casual claims

Causal claims We’d like to say: variable X --causes--> variable Y To be able to do this:  There must be co-variation between the two variables  The causal variable must come first  Directionality problem Happy people sleep well Or is it that sleeping well when you’re happy?  Need to eliminate plausible alternative explanations  Third variable problem Do Storks bring babies? A study reported a strong positive correlation between number of babies and stork sightings

Theory 1: Storks deliver babies

Theory 2: Underlying third variable

The experimental method Manipulating and controlling variables in laboratory experiments Must have a comparison At least two groups (often more) that get compared One groups serves as a control for the other group Variables Independent variable - the variable that is manipulated Dependent variable - the variable that is measured Control variables - held constant for all participants in the experiment

The experimental method Advantages Precise control possible Precise measurement possible Theory testing possible Can make causal claims Disadvantages Artificial situations may restrict generalization to “real world” Complex behaviors may be difficult to measure