A threat to external validity that occurs when attitudes ...

[arivle123]

A threat to external validity that occurs when attitudes projected onto individuals cause them to act in a certain way is called the
 
  A) Hawthorne effect.
  B) placebo effect.
  C) social desirability effect.
  D) expectancy effect.

Question 2

A threat to internal validity that involves the increased in strength due motor unit recruitment (meaning the body increases strength due to more muscle fibers being recruited by the nervous system and not muscle mass gain) is considered
 
  A) maturity.
  B) testing.
  C) instrumentation.
  D) selection.

[Chou]

Answer to Question 1

D

Answer to Question 2

B