Causation of Binet IQ Decrements.

The present study grew out of some interesting anomalies that were encountered in the process of re-standardizing the Stanford-Binet in 1972. At that time, it was found that children of pre-school age appeared to have IQ's based upon the previous standardization that averaged around 110. However, as one moved up into the elementary grades, these averages progressively dropped until, by age 9, the average was approximately 102. Several explanations of these results suggest themselves as possibilities. One is that sampling was somehow defective, and that a superior sample of pre-schoolers had been obtained. The second is that the environment of pre-schoolers had changed very drastically between the 1930's and the 1970's, and that this radically changed environment had produced an acceleration of early development, but an acceleration that was not maintained through the elementary school grades. The argument would be that schooling from age 6 on is rather similar to that of 40 years ago, and that the advantages stemming from exposure to radio, television, more books in the home etc. are effective primarily for the pre-schooler. The effect of these home factors would, primarily, accelerate development which would have occurred later under the circumstances of life a generation ago. A third possibility is that special educational programs for children, such as Sesame Street and the Electric Company, which have been developed in the late 1960's and 1970's, had produced an impact on children of pre-school age in 1971-2, but had not influenced their older brothers and sisters. There might then be a possibility that this impact would be lasting and that these young children would continue to function at a higher level than their older contemporaries. Cross-sectional data provided no basis for choosing among these explanations, so funds were sought to permit re-testing the sample of youngsters of pre-school age after a lapse of several years. By this time they would have moved ahead into the school years and it would be possible to see whether the decrement observed in crosssectional data also appeared in longitudinal data. If a decrement of the same size appeared in the longitudinal data, one could exclude two of the possible explanations advanced above: poor sampling or special educational TV programs. The remaining hypothesis of an acceleration of early development due to the total impact of an enriched culture would then seem the most reasonable one. Plans were made to re-test all of the children who had been in the age range 3 years, 4 months to 6 years, 6 months during the academic year 1971-72. The retesting was done during the academic year 1974-75 after an interval of approximately 3 years. The original testing had been carried out at seven locations, in which the basic sample had been chosen in such a way as to be representative of the national sample tested in the norming of a group scholastic aptitude test. The sampling procedures are described in the revised Stanford-Binet manual (Terman & Merrill, 1973). The same field coordinators who had managed the initial field testing all agreed to serve in the re-testing, and testing was carried out in all of the locations in which the