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By Hugo Schouppe, 2009-09-22 23:27

Rosenthal and Jacobson (1968) did the following famous but much criticized  experiment. You can download the original text at the Indiana University.

A non-verbal intelligence test, disguised as a test designed to predict academic “blooming” or “spurting”, was administered to all children of an elementary school (May 1964). After that, in each of the 18 classes, an average of 20% of the children (on average 5 pupils per class) were randomly selected. Rosenthal and Jacobson told the new teachers in September that these pupils have a potential for intellectual gains and will show a sudden and dramatic intellectual spurt over the upcoming school year. Eight months later (January 1965), all children were retested and again at the end of the school year (May 1965). It is this last test that served as the basic post-test.  For the school as a whole those children whom the teachers had been led to expect “blooming” showed a significantly greater gain in IQ score (12 IQ points) than did the control children (8 IQ points). This gain was attributed to the self-fulfilling prophecy effect. The teachers expect those children to “bloom” and changed their behaviour accordingly so that the prophecy was fulfilled. In May 1966, 2 years after the pretest, the children were given the test for the fourth and final time.

The experiment has been widely criticized. Let’s take first a closer look at the results.

As the authors themselves recognised, the effect was unequal for the different grades. The lower the grade level, the greater was the effect.  The authors tried to explain these differences because younger children (a) have less well-established reputations (b) may be more susceptible (c) can differ from older children in characteristics other than age (d) have other teachers. A possible contamination was also the fact that the retesting was done by the teachers themselves. May be, the kids weren’t smarter but they received advantage in the testing procedure (e.g. receive more time to answer). However, according to the authors, three classes were also retested by the school administrator, which means that for these three classes the children have been tested one time more than the other classes. Those results did not differ from the results of the retesting of the teachers,

L. Jussim and KD. Harber (2005) give a state of the art in “Teacher Expectations and Self-Fulfilling Prophecies: Knows and Unknowns, Resolved and Unresolved Controversies”.  You can download the full text on the website of the second author; see also Samuel S. Wineburg The Self-Fulfillment of the Self-Fulfilling Prophecy (1987). They come to the conclusion that self-fulfilling prophecies in the classroom do occur, but that these effects are typically small and whether self-fulfilling prophecies affect intelligence remains unclear.

The effect is small. In the Rosenthal study, the difference between the experimental and control group is 4 IQ points. The control group itself, however, had gained 8 IQ points over a time span of 1 year, and this without any intervention.  The effect size  -this is the difference between the experimental and the control group in standard deviation units- is .30; which is typically considered as small. The correlation between the manipulation (bloomer or not) and the IQ is .15; which is also a small relationship.

There are also some strange things in the original dataset of Jacobson & Rosenthal. Because the authors reported only change scores (difference between the pretest and the basic post test 1 year later), we have no clues about the absolute scores of the pupils. Taking a closer look at the original scores reveal that there was for example one child with a pretest on the Reasoning IQ of 17 and a post-test of 148, 110 and 112. Before the experiment, this child was severely retarded; after a few months it became highly gifted, near genius. This is, of course, very hard to believe.

In June 1966, 16 of the 18 original teachers were interviewed. Of the 72 children in the experimental group, they could only recall 18 correctly, next to the 18 control subjects which they recalled incorrectly. The teachers didn’t remember the names of the spurters. Their expectancy of he children has raised the IQ of the children with 4 points, but after 2 years these teachers didn’t know even their names.

Perhaps, these results have more to do with the fact that the teachers themselves have administered (not corrected) the tests. Because they are familiar with the tests, they can prepare the pupils for them, much like you have prepared yourself for your driver license exam. In an experiment in which the expectations were manipulated, together with the familiarity of the teachers with the test, only in the case in which the teachers are familiar with the test, an expectancy effect was discovered.

There are literally hundreds of studies on the self-fulfilling prophecy. Rosenthal himself carried out a meta-analysis over more than 300 studies. The problem with these meta-studies is that most of them don’t test the relationship between intelligence and expectancy but between expectancy and something else. About 1/3 of the studies showed a significant expectancy effect. One factor that obscures the results is the timeframe of the expectancy induction. It seems plausible that the effect is the greatest within the first week of the new school year, when the teachers hadn’t formed already an opinion about the children.

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By Hugo Schouppe, 2009-09-03 21:37

Chapter 1 of the handbook answers the question: what is psychology? What does the word mean? Where does it come from? What is the difference between psychology and common sense (folk-psychology)? Is parapsychology also a kind of psychology? …. Three very common mistakes in the explanation of behaviour are discussed: prejudice and stereotype, the fundamental attribution error and self-fulling prophecy. The chapter ends with a very brief history of psychology. Each chapter also contains some assignments. You will find the answers of the 6 assignments in chapter 1 throughout this text.

Psyche and Eros - painting of Sir Anthony van Dyck (1599-1641)

Some people think that the word psychology comes from the Greek myth of Psyche and Eros [full text] [summary] It is a very famous myth, almost as famous as King Oedipus, about a girl that was so beautiful that the goddess Aphrodite (Venus) became so jealous that she sent her son Eros (Cupid) to make Psyche fall in love with a repugnant creature. The picture at the right is the interpretation of Sir Anthony Van Dyck; a Flemish painter who was born in Antwerp [ more paintings]. There are several explanations of the myth. Maybe, Psyche’s parents, the king and queen, represent God and Matter. Psyche herself stands for the soul and her sisters for the flesh and free will. Psyche is the most beautiful, meaning that soul reigns over flesh and free will. Aphrodite represents lust who sends desire (Eros). When Psyche is not allowed to look at Eros, it can mean that one should not give in to desire. Most psychological interpretations consider the story to be the fantasy of a young women.

Psychology is about the study of human behaviour. Observing people, trying to predict their reactions, searching for their motives is what we all do, of course, when interacting with other people. But, we don’t call that psychology. It is common sense of folk psychology as you can find in proverbs. Sometimes these proverbs contain valuable information; sometimes they are quite wrong. For example, the English proverbs “Absence makes the heart grow fonder” and “Out of sight, out of mind” are quite contradictory. Do opposites attract, or do birds of a feather flock together? You can find a few more of these in Robert Epstein’s article in Psychology Today: Folk Wisdom: Was Grandma Right?  Horoscopes are a prediction of someone’s future based on the relative positions of the planets at birth.  While most university students do no endorse strong belief in astrology (90%), less than a quarter report no belief at all. One determinant of acceptance of astrology is the favourableness, or social desirability, of the particular character analysis it offers. Those for whom astrological theory provides a more attractive self-portrait are more likely to express belief in the validity of astrology (Hamilton, 2001; [full text])

The Stanford Prison Experiment of Zimbardo is a very famous experiment in psychology that illustrates the power of prejudices and stereotypes. In August 1971, about 70 young men, mostly college students eager to earn $15 a day for two weeks, volunteered as subjects for an experiment on prison life that had been advertised in the local newspaper. After interviews and a battery of psychological tests, the two dozen judged to be the most normal, average and healthy were selected to participate, assigned randomly either to be guards or prisoners. Those who would be prisoners were booked at a real jail, then blindfolded and driven to campus where they were led into a makeshift prison in the basement. Those assigned to be guards were given uniforms and instructed that they were not to use violence but that their job was to maintain control of the prison. After a few days the experiment has to be stopped because of extreme violence. You can also download the full-text of the original article, describing the experiment. There is also a fictionalized movie about it: Das experiment.

Another nice Greek myth is the one about Pygmalion [full text]. Pygmalion was a sculptor who carved a woman statue out of ivory. The statue was so beautiful that he fell in love with it and  pretended it was an actual woman. He gave it presents and treated it as if it were alive. Because the statue did not respond, Pygmalion prayed to Aphrodite, who brought the statue to life. George Bernard Shaw took the name Pygmalion as the title of his play about an English professor who turns a poor girl from the streets into a fashionable society woman. Shaw’s story was the basis of the later Broadway musical and movie My Fair Lady. Another name for the Pygmalion effect is “self-fulfilling prophecy”; which became very famous in psychology with the classic but controversial experiment of  Rosenthal and Jacobson (1968); see separate post.

Parapsychology is the study of paranormal phenomena. These are phenomena which can’t be explained by normal scientific explanations. Ray Kurzweil on the other hand is a very acknowledged scientist. On his website he make the prediction that computers will become smarter than people.

The famous print by R.C. James presents the image of a dalmatian (see handbook page 13) and is used to show that knowledge can affect our perception. However there are a lot more animals to see in this illustration, ranging from a lion a strange bizarre elephant (van Tonder et al, 2002).