• Please answer all parts of the question please!

Why is it so important to systematically study interactions and not just main effects?

Consider the following example:

An experiment was designed to test a hypothesis that stated that high-drive subjects would be able to learn a simple task much more quickly than would low-drive subjects. The hypothesis further stated that on a difficult task the opposite result would be foundlow-drive subjects would learn the task more quickly. The experimenter's operational definition of drive was each subject's score on the Manifest Drive Scale. Twenty people who scored high on the scale (high-drive) and 20 people "who scored low on the scale (low-drive) were given a difficult task to learn. The low-drive group learned the task more quickly than did the high-drive group, and the experimenter concluded that the hypothesis was correct.

• What is the the problem with this interpretation?
• What type of study could be done to correctly research the hypotheses?
• Can you think of another example where the conclusion could be misleading because of a failure to systemically examine interaction effects?