Outcomes Far More
Than We Realize
British philosopher Bertrand Russell was only half joking
when he described the powerful effect that the nationality of a scientist
can have on lab rats. "Animals studied by
Americans rush about frantically, with an incredible display of hustle and
pep, and at last achieve the desired result by chance," he wrote in
1927. "Animals observed by Germans sit still
and think, and at last evolve the solution out of their inner
Seventy-six years on, scientists have documented the power
of expectations, not only of lab researchers but also of teachers, athletic
coaches, judges and work supervisors.
"Expectation becomes a self-fulfilling prophecy,"
says Robert Rosenthal, professor of psychology at the University
of California, Riverside. "When teachers have been led to expect better
intellectual performance from their students, they tend to get it. When coaches are led to expect better athletic
performance from their athletes, they tend to get it. When
behavioral researchers are led to expect a certain response from their
research subjects, they tend to get it."
Expectation effects, also known as the Pygmalion effect,
have been documented time and again (479 studies have found that teachers'
expectations affect how students do, for instance). But
nailing down exactly how expectations are conveyed to students, athletes or
research volunteers through the nonverbal, subtle
and usually unintentional messages that Prof. Rosenthal calls "covert
communication" has been much tougher.
More alarming is how little-known the expectation effect is. And that means there is a good possibility that some
of the effects we attribute to a particular cause -- from the benefits of
smaller class sizes to the health-improving effects of wealth -- actually
reflect the power of expectations.
The power of expectations in the classroom is downright
scary. In a typical experiment, elementary-school
teachers were told that one group of kids had done extraordinarily well on
a test that predicts intellectual "blooming," and so would make
remarkable academic gains. The test seemed
prescient: After a few months, the "bloomers" it identified had
achieved statistically significant gains over the other students.
In reality, there was no such test. To
the contrary: The kids the teachers thought were bloomers included students
from every ability level as measured by a nonverbal intelligence test. So did the supposed nonbloomers. "The only difference was in the mind, and
expectations, of the teacher," says Prof. Rosenthal.
Yet those expectations produced clear academic differences.
Teachers said they viewed the bloomers as better adjusted,
more affectionate and less in need of social approval. That
leads to real differences in how teachers treated their students -- the
covert communication. Teachers with high expectations
for their students "teach [them] more and teach it more warmly,"
Prof. Rosenthal writes in the journal Current Directions in Psychological
Science. And they "tend to give greater
opportunities for responding and more differentiated feedback" to
these students, rather than a pat, "That's great, Ben." The first two factors affect student performance
Expectation effects are not confined to human expect-ees. In one set of studies, 12
experimenters were each given five rats. Six
experimenters were told that their rats were of a genetic strain that
learned like long-tailed geniuses; the other six were told that their rats
were dolts. The experimenters then spent five days
training their rats to run a maze.
From the first day, the rats identified as bright ran the
maze better -- and kept getting better.
You can guess the punch line: all the rats belonged to the
same strain. They differed only in the
experimenters' expectations for them. In this
case, the covert communication probably came from the way experimenters
with "smart" rats acted: They felt more relaxed and enthusiastic
as they worked with the rats, talked to them less (fewer outbursts of
"you stupid rat!") and handled them more.
"The extra handling of animals believed to be brighter
may have contributed to the superior learning," says Prof. Rosenthal.
The size of the expectation effect varies, but is always
statistically significant, and sometimes big. For
teachers, high expectations can raise student performance 30%. For rats, they can improve maze learning 65%.
The power of expectations is the reason studies of new
therapies are "double-blind"; not even the investigators know
which patients received the active compound and which a dummy pill. Otherwise, expecting a new drug to be beneficial might
subtly influence how investigators read an X-ray or assess a psychological
But it is not always possible to eliminate the effect of
expectations. That casts some findings, especially
in the social sciences, in a new and curious light. All
sorts of things are reported to boost student achievement, from using a
varied vocabulary with little kids to keeping class size small. But if teachers or parents expect these things to make
kids smarter, might the improvement actually reflect those expectations?
Humans may not be quite as impressionable as Russell's rats,
but we're awfully close.