In an Experiment on the Effects of Level of Motivation

Essay

In an experiment on the effects of level of motivation on the performance of typists, the researcher randomly assigned one third of her subjects to each of three levels of motivation (and then induced different levels of motivation in the three groups). She measured the average words typed per minute by each group, and found that performance was highest under medium motivation, average under low motivation, and worst under high motivation. What was the independent variable in this experiment?
a. motivation
b. typing speed
c. variation in typing speed
d. manipulation of typing speed