 of hereditary and environmental factors; the parents were retarded and did not provide a stimulating home environment for the children.
INTELLIGENCE DIFFERENCES BETWEEN GROUPS
Gender differences In these days of an increased sexual equality across many activities, the question arises: "Are women as intelligent as men?" The answer is unclear. The sexes differ in specific abilities. Females are typically superior in verbal abilities and in items concerned with social relations. They also perceive details more quickly and accurately and do better on tests of memory. Males, on the other hand, surpass women on items that involve spatial, numerical, and mechanical performance. These differences, however, are averages. The variance within each sex is much greater than the difference in results between the sexes. In scores of overall intelligence, the two sexes seem to be about equal. All differences are restricted to specific abilities, not to the composite that we call intelligence. It is debatable, however, whether the differences in specific abilities are due to biological or cultural factors.
A recent study by Stumpf and Stanley (1999) investigating gender differences in scholastic achievement, suggests that the historic differences between the sexes may not be decreasing as much as earlier suspected. They examined the performance of over eight hundred thousand test takers on the College Board Advanced Placement (AP) tests and the College Board Scholastic Assessment Test (SAT). They found that males showed advantages mainly in Physics, Computer Science, Chemistry and Calculus; but also in Economics, Government, U.S. History and Biology. Females showed advantages in Spanish and French Literature, English Literature, and Art History. This pattern remained relatively stable over the period of the study, from 1984 to 1996, even though the subjects changed. There has been a decline, however, in the advantages which males show in Computer Science. The AP tests were half multiple-choice and half open-ended items, compared to the SAT which was all multiple choice. Gender differences favoring males appears larger on those tests which are multiple-choice, which has been observed in earlier studies.
Socioeconomic classIntelligence differences between socioeconomic classes are well documented. In fact, one researcher (Tyler, 1956) concluded that the relationship of IQ scores to socioeconomic level was one of the best documented facts in mental test history. This was indicated earlier in Terman's study of gifted children, and more evidence will be presented in the next module. On the average, higher IQ's are found in families of the upper socioeconomic levels than in those of the lower levels.
IQ scores reflect educational opportunities. This is indicated in the data on socioeconomic levels. Children from disadvantaged groups frequently have inferior educational facilities, and their attitudes toward education are less favorable. The educational opportunities among various racial groups vary markedly. Therefore, one would expect that differences in average IQ would be apparent between various racial groups. Usually it is not really possible to determine whether the differences are due to racial or socioeconomic factors. Tulkin and Nembrough (1968) used statistical procedures to control for differences in such variables as broken homes, maternal employment, crowded living quarters, and so on. Under these controls their studies with upper social class grade school children indicated no difference between races.
Race differences. Many comparisons have been made between black and white children. Three conclusions have been found repeatedly. Black children, on the average, achieve lower IQ scores than white children. The second conclusion is that scores for black and white children overlap a great deal. Both of these results are shown in Figure 15. The third consistent finding is that the IQ scores of black children rise when their educational opportunities are improved. This fact, plus the knowledge that an enriched environment causes an i