Effect of scopolamine on memory. The drug scopolamine is often used as a sedative to induce sleep in patients. In Behavioral Neuroscience (Feb. 2004), medical researchers examined scopolamine’s effects on memory with associated word pairs. A total of 28 human subjects, recruited from a university community, were given a list of related word pairs to memorize. For every word pair in the list (e.g., robber-jail), there was an associated word pair with the same first word, but a different second word (e.g., robber-police).The subjects were then randomly divided into three treatment groups. Group 1 subjects were administered an injection of scopolamine, group 2 subjects were given an injection of glycopyrrolate (an active placebo), and group 3 subjects were not given any drug. Four hours later, subjects were shown 12 word pairs from the list and tested on how many they could recall. The data on number of pairs recalled (simulated on the basis of summary information provided in the research article) are listed in the accompanying table. Prior to the analysis, the researchers theorized that the mean number of word pairs recalled for the scopolamine subjects (group 1) would be less than the corresponding means for the other two groups.
a. Explain why this is an independent-samples design.
b. Identify the treatments and dependent variable.
c. Find the sample means for the three groups. Is this sufficient information to support the researchers’ theory? Explain.
d. Conduct an ANOVA E-test on the data. Is there sufficient evidence (at α = .05) to conclude that the mean number of word pairs recalled differs among the three treatment groups?
SCOPOLAMINE
Group 1 (Scopolamine): | 5 | 8 | 8 | 6 | 6 | 6 | 6 | 8 | 6 | 4 | 5 | 6 |
Group 2 (Placebo): | 8 | 10 | 12 | 10 | 9 | 7 | 9 | 10 | ||||
Group 3 (No drug): | 8 | 9 | 11 | 12 | 11 | 10 | 12 | 12 |
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