Experimental Research and Educational Technology

What IS Experimental Research?

The experimental method in educational psychology was first used at the beginning of the 20th century by Edward Thorndike in his classic studies of learning. Researchers were interested in studying the effect of changes in the environment or treatments on phenomena such as learning and perception. Research designs were needed to control the experimental conditions so that differences between groups on the dependent (outcome) variable could be attributed to the effect of the independent (treatment) variable. The results were highly controlled studies with high internal validity that allowed researchers to compare the results of the experimental group to the control group, while ruling out rival hypotheses and effects from extraneous factors. For example, if you were attempting to determine the minimum size letters to use on a presentation slide, you might ask an experimental group and a control group to identify nonsense words of different sizes (BUV, NAQ, etc.). Such a study would have high internal validity as learners in the two treatments could not guess a word by recognizing a letter or two. Similarly, the presentation would be in a room where the researcher could control the ambient lighting and maintain consistency across all participants during different testing times. By changing just the height of the letters, the independent variable, the researcher can have confidence that any difference is due to the height of the letters and not from hints derived from words or sunlight on the screen in only the afternoon.

A reasonable follow-up study might be a similar study conducted in a typical classroom using phrases or words rather than random letters. In the follow-up study, the sunlight from the window shining on the screen could affect viewing of the letters and the words could provide contextual hints leading to a guessing of the phrases or a word by recognizing a few letters. While the follow-up study would have the advantage of higher external validity by being conducted in a realistic setting, it would have lower internal validity, thus limiting attributions of the experimental treatment effect to just letter size. Such a study is an example of research [Page 287]practice in the field of educational technology that seeks to find a balance between internal and external validity levels. Balancing internal and external validity in studies is a characteristic of fields that depend on both basic and applied research.

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