An experimenter tests the hypothesis that physical exercise improves mood. Subjects in the experimental group participate on Monday and Tuesday and those in the control group on Wednesday and Thursday. What is the extraneous (confounding) variable?

A. The exercise

B. The day of the week

C. The hypothesis

D. The mood (degree of happiness)

B. The day of the week

Explanation:

Extraneous variable: In a psychological experiment, the term extraneous variable is also denoted as confounding variable and is defined as a variable that an experimenter or researcher is not studying intentionally or purposefully while conducting an experiment or research. The extraneous variable is the variables that are considered as undesirable in an experiment and it could affect the data being collected negatively.

In the question above, the extraneous variable is the day of the week.