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