Two Groups of Graduate Students Were Given Rats and Were

Multiple Choice

Two groups of graduate students were given rats and were told to teach them how to run mazes. Group 1 was told that they had "very smart" rats that should learn quickly. Group 2 was told that they had "very stupid" rats that should learn slowly. In actuality, neither group was any different, and the rats were randomly assigned. In spite of that, when the experiment concluded, Group 1 rats had learned the maze much more quickly. How can that be explained?

A) experimenter effect .
B) placebo effect
C) subject bias
D) treatment effect