According to the overjustification effect, reinforcements that praise people tend to intrinsic motivation, and reinforcement that seeks to control people intrinsic motivation

Increase; decrease

Explanation:

The overjustification effect is a phenomenon in which being rewarded for doing something actually diminishes intrinsic motivation to perform that action. It occurs when an external incentive decreases a person's intrinsic motivation to perform a behavior or participate in an activity. People see external reinforcement as a coercive force hence having a reduced intrinsic motivation.

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.