23 A group of college students is participating in a memory study that involves performing the same task each day under different circumstances; however, as each day goes by, the students are...

23

A group of college students is participating in a memory study that involves performing the same task each day under different circumstances; however, as each day goes by, the students are obviously getting more comfortable with completing the task. Which threat to internal validity has confounded this study?

a. History

b. Selection bias

c. Practice

d. Fatigue