In Exercise 4.134 on page 279, we used the data in Table 6.13 to conduct a randomization test to see if there was evidence that electrical stimulation of the brain helped people solve a problem that requires fresh insight. Explain why it would not be appropriate to conduct this test using the normal distribution and the formulas in this section.

Table 6.13

Data from 4.134

If we have learned to solve problems by one method, we often have difficulty bringing new insight to similar problems. However, electrical stimulation of the brain appears to help subjects come up with fresh insight. In a recent experiment conducted at the University of Sydney in Australia, 40 participants were trained to solve problems in a certain way and then asked to solve an unfamiliar problem that required fresh insight. Half of the participants were randomly assigned to receive non-invasive electrical stimulation of the brain while the other half (control group) received sham stimulation as a placebo. The participants did not know which group they were in. In the control group, 20% of the participants successfully solved the problem while 60% of the participants who received brain stimulation solved the problem.

Not Solved Treatment Solved 16 Sham 4 Electrical 12