Answer:
instrumentation
Step-by-step explanation:
As part of an experiment on the effects of behavior modeling, a set of raters are evaluating prosocial behavior in a series of videotapes of a preschool class. Initially, the raters were quite strict in their ratings, but after 3 hours of rating, their criteria had changed.the type of threat to internal validity that occur is instrumention.
Instrumentation is the e changes in the instrument, observers, or scorers which may produce changes in outcomes.