PSYCHOLOGICAL RESEARCH

DESIGN & METHODS

Outcome A: Foundations & Methods

Overview of the Scientific Method

Components of Research

Critical Thinking

• Basis for research (stems from curiosity).

• Helps assess reliability & claims.

Hypothesis• Testable prediction.

Operational Definition

• Descriptions of the EXACT operations or methods.

Components of Research

Variables

• Factors or characteristics in research.

• Can be manipulated or measured.

Data

• #’s or descriptions representing research findings

• Provide the basis for research conclusions.

Theory

• Statements that can account for, or predict behavior.

• Subject to critical thinking.

Selecting Participants for Research

Random SampleParticipants selected from the population

(whose members had an equal chance of being selected).

Representative SampleThe sample of participants accurately

reflect the greater population.Attempt to represent as many characteristics

as possible (age/gender, etc).

Population SamplingProcess of selecting participants who are members of the

population.

The Experiment

•An experiment involves a set of controlled conditions that aims to confirm a hypothesis

•Hypothesis refers to a statement of cause and effect:

•“Higher environmental temperatures lead to more aggression”

•“Exposure to marijuana increases appetite”

Experimental Variables

•To test a hypothesis, an experimenter defines the variables of the hypothesis:•Cause: Independent variable (IV)

•Marijuana: Plain cigarette versus cigarette containing 5 mg of THC (the active ingredient in marijuana)

•Effect: Dependent variable (DV)•Appetite: Grams of ice cream consumed in 1 hour

•The experimenter manipulates the IV and measures the DV to test the hypothesis

Research Issues•Controls are important for determining causality

• The only difference between the experimental and control groups is the presence or absence of the IV.

•Placebo effects represent changes in behavior that are related to expectations of a treatment• Placebo effects are controlled by a blind control group (the

subject does not know whether the treatment was given or not)

•Experimenter bias refers to expectations that influence subject behavior• Experimenter bias can be controlled using double blind

procedures (experimenters and subjects are ignorant of treatment conditions)

100 Depressed Subjects

50 - Drug

50 - No Drug

38 Improve

8 Improve

100 Depressed Subjects

50 - Drug

50 - Placebo

38 Improve

20 Improve

Placebo Effect

Non-Experimental Research

•Naturalistic observation refers to the systematic recording of behavior in a natural state or habitat•E.g. Jane Goodal observing apes in the wild

•Surveys are instruments designed to sample attitudes or behaviors •Asking persons at a rally how they feel about animal rights issues

•A case study is an in-depth study of a single person•Freud used the case study method to probe anxiety

Correlation Techniques

•The correlation technique indicates the degree of association between 2 variables

•Correlations vary in direction:•Positive association: increases in the value of variable 1 are associated with increases in the value of variable 2

•Negative association: increases in the value of variable 1 are associated with decreases in the value of variable 2

•No relation: values of variable 1 are not related to variable 2 values

Correlations•Correlations also vary in the strength of the association•Zero correlation: no relationship between the 2 variables

•Strong correlation: knowing the value of one variable permits one to accurately estimate the value of the other variable• Strong correlation can be positive or negative

•Correlations can be seen in scatter plots

Correlation

Correlation

Correlation

Correlation

Correlation

Correlation

Correlation

Correlation

Correlation

EXPERIMENTAL METHOD

From “The Happiness Study”

•Hypothesis: Engaging in happiness exercises increases

levels of happiness.

Hypothesis

Engaging in happiness exercises increases levels of happiness.

Critical Thinking

What were the researchers curious to know more about?

• Happiness

• How can we boost happiness?

• Do happiness exercises work?

• Are the effects permanent?

• Is there a placebo effect?

Placebo Effect = Power of Suggestion

Experimental Variables

Independent Variable

(IV)

Factor or condition being manipulated by experimenter.

Happiness Exercises

Dependent Variable

(DV)

Factor being measured.

Happiness

Control

Outside of the variables, ALL

other conditions must be equal!

Experimental Subject Groups

Experimental Group

Exposed to the IV

Participants who participate in the various happiness

exercises.

Control Group

Not exposed to the IV

Serves as a basis for comparison

Participants who participate in the placebo exercise