Rosenthal and Jacobson (1966) sought to test the experimenter expectancy effect by
examining how much of an outcome teachers' expectancies could have on a group of children.
Earlier investigations in this area were also conducted by Rosenthal (1963). He worked with
children in a research lab, giving each one a rat and telling them it was either bred for
intelligence or for dullness. The children were put in charge of teaching the rats how to learn
mazes. Rosenthal's results showed that the rats that were believed by the students to be smart,
were able to learn the mazes much quicker. What the children did not know, i.e., what
Rosenthal had kept hidden, was that the rats were chosen at random. There were no rats that
were especially bright or dull. Another case of the experimenter expectancy effect was that of
the horse known as "Clever Hans". It seemed to be able to read, spell, and solve math problems
by kicking his leg a number of times.
The horse was tested and passed, but what the experts did
not realize was that their own hopes for the horse to answer the questions, were giving the horse
signs on which he based his answers. That is, if someone on the committee raised his/her
eyebrows in anticipation of the oncoming correct answer, the horse would stop stomping. Once
again, the experimenter's cues decided the outcome of the tests. Acting on these results,
Rosenthal and Jacobson hypothesized that teacher's expectancies would cause them
unintentionally to treat the students they thought to be bright in a different manner than those
they thought to be average or even less bright.
Rosenthal and Jacobson used some materials that were important in the completing their
investigation. The experimenters used students and their teachers as the subjects...