Dr Treadwell Is Designing a Study to Test the Effectiveness

Dr. Treadwell is designing a study to test the effectiveness of a new memory enhancement technique. He has two research assistants who will be carrying out the research for him and because he is curious, he tells one of the research assistants to
Expect the technique to significantly improve memory while he tells the other assistant to expect only a moderate improvement. Neither research assistant mentions their
Expectations to the participants. After the study has been completed, Dr. Treadwell
Notices that each research assistant obtained results consistent with what they had been led to expect. Participants who were studied by the first research assistant actually
Showed a significant improvement in memory while participants who were studied by
The second research assistant only showed a moderate improvement. This result is most likely an example of:

A) the placebo effect.
B) experimenter expectancy effects.
C) social desirability bias.
D) the double-blind procedure.