RESEARCH METHODS

AP PsychologySeptember 15, 2014

The Scientific Method - in Psychology Starts with a THEORY

An explanation using an integrated set of principles that organizes observations and predicts behaviors or events

E.g. The root of depression is low self-esteem. Theory produces testable predictions, called

HYPOTHESES. They give direction to research. They specify what results would support or

disconnfirm the theory. E.g. People who report poorer self-image on a

particular scale would score higher on a depression scale.

The Scientific Method - in PSYCHOLOGY, cont’d. Testing can be one of three types:

DESCRIPTIVE CORRELATIONAL EXPERIMENTAL

Eventually, testing leads to a revised theory, which better organizes and predicts what we know about the topic.

Types of Studies

They vary by purpose and methodology.

Three main types: Experimental Correlational Descriptive

EXPERIMENTAL STUDIES

Only way to study cause and effect One or more factors are manipulated

in order to observe cause & effect Factor that is manipulated =

INDEPENDENT VARIABLE Factor that is being tested (or depends

on the independent variable) = DEPENDENT VARIABLE

“Conditions” in an Experiment Experimental

exposed to independent variable Control

not exposed to independent variable serves as a comparison

Variables

Which variable is which? In a study to determine the effects of

caffeine consumption on class participation

In a study to determine the effects of video game playing on aggressive behavior

In a study to determine the effect of a certain medication on anxiety symptoms

How are variables measured in an experiment? Operational definitions

Specify precisely what procedures will be used to measure and manipulate variables

E.g. “Hunger” = “hours without eating” This allows for REPLICATION (repeating

the study in a different situation)

How do researchers ensure the groups are “equal”? Random assignment

Putting subjects into experimental and control conditions by chance

Minimizes preexisting differences Allows researchers to say that results are

probably due to manipulation of the independent variable