Evidence from an analysis of 2000 errors and omissions made in IQ tests by a small sample of schoolchildren, undergoing vitamin and mineral supplementation, that speed of processing is an important factor in IQ performance

A sample of schoolchildren was administered vitamin and mineral supplements or a placebo triple-blind for 10 weeks to examine possible differences in IQ performance resulting from enhanced nutrition. A significant difference in increased non-verbal IQ scores between the active supplement and placebo groups was found, but no difference in verbal IQ scores between the two groups was demonstrated. An analysis of the errors and omissions made in the IQ tests indicates that the error rate for the supplemented group remained stable over the 10 weeks but that the number of omissions dropped significantly. Almost all the omissions made by the children in the first IQ test were at the end of the paper when the children ran out of time and so were unable to finish the paper. After 10 weeks of supplementation, however, considerably more non-verbal IQ questions were completed and since the error rate remained the same this resulted in significant gains in non-verbal IQ. These data suggest that speed of processing is a significant factor in IQ performance and presumably in intelligence. In the light of this analysis no increase in verbal IQ scores could have been expected since almost all children completed all the questions on the first verbal IQ test paper. There was simply no room for improvement in verbal IQ to occur.