SUMMER READING ASSIGNMENT
Forty Studies that Changed Psychology: Explorations into the History of Psychological Research
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WHAT YOU EXPECT IS WHAT YOU GET
Rosenthal, R., SL Jacobson, L. (1966).
Teachers' expectancies: Determinates of pupils' IQ gains
, 19, 115-118.
We are all familiar with the idea of the self-fulfilling prophecy. One way of describing this concept is to say that if
we expect something to happen in a certain way, our expectation will tend to make it so.
prophecies really do occur in a predictable way in everyday life is open to scientific study, but psychological
research has demonstrated that in some areas they are a reality.
The question of the self-fulfilling prophecy in scientific research was first brought to the attention of psychologists
in 1911 in the famous case of “Clever Hans,” the horse of Mr. von Osten (Pfungst, 1911).
Clever Hans was a horse
that was famous for being able to read, spell, and solve math problems by stomping out answers with his front hoof.
Naturally there were many skeptics, but when a committee of experts tested Hans’s abilities, they were found to be
genuinely performed without prompting from Mr. von Osten.
But how could any horse (except possibly for Mr.
Ed! [1950’s television show that featured a talking horse!]) possess such a degree of human intelligence?
psychologist, O. Pfungst, performed a series of careful experiments and found that Hans was receiving subtle
unintentional cues from his questioners.
For example, after asking a question, people would look down at the
horse's hoof for the answer.
As the horse approached the correct number of hoof-beats, the questioners would raise
their eyes or head very slightly in anticipation of the horse completing his answer.
The horse had been conditioned
to use these subtle movements from the observers as signs to stop stomping, and this usually resulted in the correct
answer to the question.
So, you might ask, how is a trick horse related to psychological research? Well, the Clever Hans findings pointed
out the possibility that observers often have specific expectations or biases that may cause them to send covert and
unintentional signals to a subject being studied.
These signals, then, may cause the subject to respond in ways that
are consistent with the observers' bias and, consequently, confirm their expectations.
What all this finally boils
down to is that an experimenter may think a certain behavior results from his or her scientific treatment of one
subject or one group of subjects compared with another. Actually the behavior may result from nothing more than
the experimenter's own biased expectations.
If this occurs, it renders the experiment invalid.
This threat to the
validity of a psychological experiment is called the
experimenter expectancy effect
Robert Rosenthal, a leading researcher on this methodological issue, has demonstrated the experimenter expectancy