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E-Prime User’s Guide

Appendix B: Considerations in Research

Page A-19

-- Contributed by James St. James, Millikin University

While many of the persons using E-Prime are intimately familiar with the intricacies of research,

many are not, or are just beginning to learn. In this chapter, we present a brief overview of

experimental research, including review of some basic terms and ideas. It is not the purpose of

this document to serve as an introduction to the use of E-Prime. Rather, its purpose is to aid the

user of E-Prime in the conceptual development of experiments, and to consider a number of

broad classes of issues regarding experimentation in psychology. If you feel that you are quite

familiar with research methodology as it pertains to psychological research, feel free to skip this

chapter. This chapter is particularly useful for those in need of a ‘refresher course’ in research

methods.

Experimental Design Considerations

We begin with a consideration of some basic principles of research design. Then we consider a

number of details of the single-trial, reaction time paradigm that is the basis of much of current

psychological research. Skip any sections that cover familiar material. Parts of what we include

below will seem too obvious to some, but we hope to aid the person using E-Prime who will

benefit from a reminder of basic terms, or who is just beginning the process of learning to do

research. Our emphasis here is on experimental research, and our examples lie there, but

observational and correlational research requires consideration of many of the same points.

Because what follows is not a complete textbook of research methods, the references cited are

largely to general sources. The reader is encouraged to go to those sources for more complete

coverage and primary references. Many textbooks of research methods in psychology are

available that will treat the general topics below in more detail. Most do not include

considerations specific to single-trial reaction-time procedures, which we detail.

Definitions

Because they are so widely used in our discussion, we begin by defining dependent and

independent variables and controls.

Dependent and Independent Variables

In designing and setting up an experiment using E-Prime, independent and dependent variables

will have to be named. Dependent variables (DV’s) are measures of outcome, such as reaction

time and accuracy. Independent variables (IV’s) are the aspects of an experiment that are

manipulated by the experimenter. Note that, in an experiment, the value of the outcome measure

is assumed to depend upon, or be caused by, the condition under which the subject was tested—

the level of the independent variable. Hence, it is a dependent variable.

Independent variables have two or more levels, which define the conditions under which the

subject is tested. Examples would be type of stimulus, timing of stimuli, or any other aspect of