PSYC 200Week #9

Thinking Like a Psychologist Part 33 1/3

Agenda

Roll call Essay #2 (missing several) APA Mastery Test – see me if

questions Review Control, Research Methods, and

more Intuitions Test Probability, Chance, and the Popular

Image of Psychology

Review

Does correlation prove causation? Why or why not?

What is the principle of faslifiability? What are the problems with

testimonial evidence?

Control

Necessary to make causal inferences and rule out alternative explanations

When a researcher holds everything in 2 (or more) different situations constant except for a particular variable

Requires that we separate and individually control variables that may naturally occur together

Then if the outcome changes, the only explanation is the variable that changed… Outcome = Dependent Variable Manipulated variable = Independent Variable

Control (cont’d)Variables Quiet Condition Noisy Condition

Noise Level (IV) Low High

IQ (EV) Average Average

Room Temperature (EV) 70° 82°

Sex of Subjects (EV) 60% Female 60% Female

Task Difficulty (EV) Moderate Moderate

Time of Day (EV) Morning Afternoon

Control (cont’d)

The Control Group A group of participants that receives no (or

alternative) treatment Why important?

Examples of importance Clever Hans Facilitated Communication

Separation of Variables Must rule out alternative explanations; therefore

must create artificial situations where variables that naturally occur together are teased apart.

Video – Prisoners of Silence

Intro to Research Methods

Research Methods

There are 6 basic categories of scientific method that virtually all research falls intoResearch

Non-Experimental Experimental

Naturalistic Observation Quasi-Experimental

Survey

Relational Research

Field Study Experimental

Research Methods –Naturalistic Observation

Addresses most basic scientific question: “What is out there?”

Requires operational definition of events to be observed

Observer must be unobtrusive, and design must be nonreactive

Research Methods –Field-Based Research

Like naturalistic observation, conducted in real-world settings

Goal is to establish natural relations among events

Observer must be unobtrusive, but methods are intentionally reactive

Research Methods –Survey Research

Appropriate to the study of private behaviors

Two primary styles: Interviews (structured/unstructured) Questionnaires

(structured/unstructured)

Research Methods –Relational (Correlational) Research

Goal to verify systematic (usually linear) relations among events

Strengths/directions of relations generally expressed in form of

correlation coefficient (rxy)

Research Methods –True Experiment

Goal: to establish a cause-effect relationship among events Does low-fat diet cause decrease in

cancer risk? Does exposure to violent video games

cause increase in violent behaviors? Does spaced study cause increase in

memory accuracy and retention? Do genetic variations cause sexual

preference?

Research Methods –True Experiment

Requires:random assignment of participants to at least two

equivalent conditionsmanipulation of one factor (independent variable,

or IV) in one condition (experimental), leaving it unchanged in other condition (control)

measurement of one other factor in both conditions (factor called dependent variable, or DV; measurement instrument called dependent measure, or DM)

Research Methods –True Experiment

Concludes:if groups are NOT equivalent with

respect to DV, and if the difference between the groups is so big it

probably did not happen by chance, thenmanipulation of the IV caused the difference in the

DV

Research Methods –Quasi-Experiment

Goal also to establish cause-effect relations among events

Required when random assignment is not possible, becausemust use pre-existing groups, orIV impossible to manipulate directly, orIV unethical/illegal to manipulate directly

Research Methods Review

Name 6 categories of scientific research

Which method of research can be used to establish cause and effect relationships?

Gradual Advancement

Converging Evidence

Gradual Synthesis Model Great Leap

Remember, the goal of science is really to get less and less WRONG.

Multiple Causation

Most phenomena are caused by multiple (not just one event)

Examples? There’s usually no “magic bullet” or

“missing key”