9.61 Hypnosis and the Stroop effect: In Chapter 1, you were given an opportunity to complete the Stroop test, in which color words are printed in the wrong color; for example, the word red might be printed in the color blue. The conflict that arises when we try to name the color of ink the words are printed in but are distracted when the color word does not match the ink color increases reaction time and decreases accuracy. Several researchers have suggested that the Stroop effect can be decreased by hypnosis. Raz, Fan, and Posner (2005) used brain-imaging techniques to demonstrate that posthypnotic suggestion led highly hypnotizable people to see Stroop words as nonsense words. Imagine that you are working with Raz and colleagues and your assignment is to determine whether reaction times decrease (remember, a decrease is a good thing; it indicates that participants are faster) when highly hypnotizable people receive a posthypnotic suggestion to view the words as nonsensical. You conduct the experiment on six participants, once in each condition, and receive the following data; the first number is reaction time in seconds without the posthypnotic suggestion, and the second number is reaction time with the posthypnotic suggestion: Participant 1 12.6, 8.5 Participant 2 13.8, 9.6 Participant 3 11.6, 10.0 Participant 4 12.2, 9.2 Participant 5 12.1, 8.9 Participant 6 13.0, 10.8

a. What is the independent variable and what are its levels? What is the dependent variable?

b. Conduct all six steps of a paired-samples t test as a twotailed test. Be sure to label all six steps.

c. Report the statistics as you would in a journal article.

d. Now let’s look at the effect of switching to a one-tailed test. Conduct Steps 2, 4, and 6 of hypothesis testing for a onetailed paired-samples t test. Under which circumstance—a one-tailed test or a two-tailed test—is it easier to reject the null hypothesis? If it becomes easier to reject the null hypothesis under one type of test (one-tailed vs. two-tailed), does this mean that there is a bigger mean difference between the samples? Explain.