Question

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 can keep the cursor on the dot. It was 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 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 explain why the experiment is confounded.                                                                                            

3a. [1 point] The experimenter assigned ten 20-year-old males to the no-noise condition and ten 60-year-old females to the noise condition.

3b. [1 point] The experimenter urged the subjects in the no-noise condition to try very hard, but forgot to encourage the subjects in the noise condition.

3c. [1 point] Subjects in the no-noise condition performed the experiment at 9:00 A.M. and subjects in the noise condition performed the experiment at 4:00 P.M.

3d. [1 point] The experimenter let participants choose which group (no-noise or noise condition) they wanted to be assigned to.

Answer 1

(3a)

The experimenter assigned ten 20-year-old males to the no-noise condition and ten 60-year-old females to the noise condition.

The Confounding Variable that confounds this experiment by letting an extraneous variable vary systematically with the independent variable of noise condition: the natural effects of noise on the performance of a tracking task between males and females are quite different. So, in case the experiment yields difference in noise levels, we cannot be certain that it is due only to environmental noise because the variation may be attributed to gender also.

(3b)

The experimenter urged the subjects in the no-noise condition to try very hard, but forgot to encourage the subjects in the noise condition.

The Confounding Variable that confounds this experiment by letting an extraneous variable vary systematically with the independent variable of noise condition: the urging of the experimenter only to no - noise condition. So, in case the experiment yields difference in noise levels, we cannot be certain that it is due only to environmental noise because the variation may be attributed to the urging of the experimenter only to no - noise condition also.

(3c)

Subjects in the no-noise condition performed the experiment at 9:00 A.M. and subjects in the noise condition performed the experiment at 4:00 P.M

The Confounding Variable that confounds this experiment by letting an extraneous variable vary systematically with the independent variable of noise condition: environmental conditions at 9 A.M. will not be the same at 4.00 P.M. So, in case the experiment yields difference in noise levels, we cannot be certain that it is due only to environmental noise because the variation may be attributed to the environmental conditions at 9 A.M. will not be the same at 4.00 P.M. also.

(3d)

The experimenter let participants choose which group (no-noise or noise condition) they wanted to be assigned to.

The Confounding Variable that confounds this experiment by letting an extraneous variable vary systematically with the independent variable of noise condition: Randomized assignment of participants in the 2 groups not adhered to. So, in case the experiment yields difference in noise levels, we cannot be certain that it is due only to environmental noise because the variation may be attributed to the Randomized assignment of participants in the 2 groups not adhered to also.