Reading tongue twisters. According to Webster’s New World Dictionary, a tongue twister is “a phrase that is hard to speak rapidly.” Do tongue twisters have an effect on the length of time it takes to read silently? To answer this question, 42 undergraduate psychology students participated in a reading experiment (Memory & Cognition, Sept. 1997).

Two lists, each composed of 600 words, were constructed.

One list contained a series of tongue twisters, and the other list (called the control) did not contain any tongue twisters.

Each student read both lists, and the length of time

(in minutes) required to complete the lists was recorded.

The researchers used a test of hypothesis to compare the mean reading response times for the tongue-twister and control lists.

a. Set up the null hypothesis for the test.

b. For each student, the researchers computed the difference between the reading response times for the tongue-twister and control lists. The mean difference was .25 minute with a standard deviation of .78 minute.

Use the information to find the test statistic and p-value of the test.

c. Give the appropriate conclusion. Use a = .05.