Class: Statistics for the Behavioral Sciences

Questions:

6. An experimenter is investigating the effects of noise on the performance of a tracking task. The task is to use a mouse to keep a cursor on a computer screen on a randomly moving target dot. The dependent variable is the amount of time a person is able to keep the cursor on the dot. The experimenter hypothesized that subjects performing the task when no environmental noise is present will keep the cursor on the target for a greater amount of time than subjects who perform the task while listening to a loud noise. Each action by the experimenter that is described next confounds this experiment by letting an extraneous variable vary systematically with the independent variable of noise condition. For each action, identify the extraneous variable confounding the experiment and then explain why the experiment is confounded.

6a. The experimenter assigns ten 20-year-old males to the no-noise condition and ten 60-year-old males to the noise condition.

6b. The experimenter urges the subjects in the no-noise condition to try very hard, but does not encourage the subjects in the noise condition.

6c. The experimenter assigns males to the no-noise condition and females to the noise condition.

6d. The experimenter assigns physical education majors to the no-noise condition and social science majors to the noise condition.

6e. Subjects in the no-noise condition do the experiment between 9:00 and 10:00 A.M., and subjects in the noise condition do the experiment between 4:00 and 5:00 P.M.