Dr. LaGuardia is a cognitive neuroscientist who is interested in the effect of brain concussions on the ability to recognize faces. He conducts a quasi-experimental study in which he examines football...

 Dr. LaGuardia is a cognitive neuroscientist who is interested in the effect of brain concussions on the ability to recognize faces. He conducts a quasi-experimental study in which he examines football players before and after the regular season using the Benton Facial Recognition Test (a published, widely used measure of one’s ability to recognize faces) to compare those who received concussions to those who did not. He finds that players who had concussions during the regular season performed worse on the Benton Facial Recognition Test than did players who did not experience concussions.

In analyzing the data, Dr. LaGuardia finds that there was no pretest difference in Benton Facial Recognition scores. However, he does find that the football players who received concussions had worse visuo-spatial awareness before the study. Which of the following threats to internal validity should he be concerned with?

a.  Regression to the mean

b.  History threat

c.  Design confounds

d.  Maturation threat

Answer is C, but why? (Please type, no handwriting)