The generality of ability factor structure in adulthood and old age was investigated. Data were analyzed for 198 young individuals (15-32 years), 156 younger old individuals (53-68 years), and 156 older old individuals (69-91). Variables were nine tests marking three ability factors. (Author/CTM)

Stephens et al. (EJ 055 112) committed a serious methodological error in holding chronological age constant in their IQ measures and allowing it to vary in their Piagetian developmental measures. This error is unrelated to differences in factor rotation methods used by these authors and was not answered in their reply. (CTM)

These authors cite their own study of the relationship between traditional measures of intelligence and Piagetian measures of cognitive development in support of Glass and Stephens' contention that there are important qualitative differences. They question Humphreys' and Parsons' conclusions on both substantive and factor theoretical grounds. (CTM)