DrHans Zarkoffis Testing Groups of Teenagers and Senior Citizens on Their

Multiple Choice

Dr.Hans Zarkoffis testing groups of teenagers and senior citizens on their ability to imagine the rotation of objects in space.He finds that the teenagers perform much better than the seniors.Dr.Zarkoffinitially suspects that his results are due to the declining mental ability of the senior group,but then realizes that the teenagers have had more experience with video games.This is an example of a____effect.

A) cohort
B) mortality
C) history
D) testing