Bias in Mental Testing; (p 107)
Arthur Jensen; 1980
Misjudgments of an individual’s general intelligence are usually a result of basing judgment on an atypical aspect of the person’s behavior. Almost everyone may do or say something that is particularly clever or bright or sagacious now and then, or may behave quite stupidly on occasion. If we give too much weight to these atypical occurrences in our subjective judgment of a person’s mental capacity, we are apt to take exception to his or her tested IQ. Parents seem especially prone to judge their own children by their atypical performances. Each person’s abilities vary about his own mean, and we usually notice the deviations more than the mean. Prejudices and the like may cause us consistently to give greater weight to the positive deviations than to the negative for some persons and vice versa for others. School teachers, who observe large numbers of children of similar age over a wide range of ability, are usually better judges of intelligence than parents are. I once had occasion to interview independently the mothers and the classroom teachers of a number of children to whom I had given individual IQ tests. I found that the teachers had a much better estimate than the mothers of a given child’s rank in the total distribution of IQs. In giving their reasons for their estimate of a particular child’s IQ, the teachers usually noted the child’s typical behavior in cognitively demanding situations, whereas mothers more often pointed out exceptional instances of clever behavior. On this basis, low-IQ children especially are often rated average or above by their parents. Very-high-IQ children, on the other hand, are often underrated by their parents, who are usually surprised to learn that their child is quite exceptional. Parental judgments of children’s intelligence tend to cluster more closely around the mean (or slightly above) than do the children’s IQs. Personality factors affect subjective judgments, too, for both parents and teachers. The socially outgoing, extraverted child tends to be overrated as compared with the more shy, quiet, or introverted child.