Many aspects of cognition decline from middle to late adulthood, but the dimensionality and generality of this decline have rarely been examined. We analyzed 20-year longitudinal data of 6203 middle-aged to very old adults from Greater Manchester and Newcastle-upon-Tyne, UK. Participants were assessed up to eight times on 20 tasks of fluid…

The study investigates the effects of intelligence, perceptual speed and age on intraindividual growth in attentional speed and attentional accuracy over the course of a 6-minute testing session. A sample of 193 subjects completed the Advanced Progressive Matrices and the Vienna Matrices Test representing intelligence, the tests Alertness and…

Tested 8 individuals with mental retardation or autism and 16 individuals without either condition for their ability to detect a form in a random-dot kinematogram. The presence and generalization of training effects in those who initially did not meet criterion performance suggests that initial failures may be due in part to postperceptual…

The latency and amplitude of the P300, an event-related potential, during the performance of a memory-scanning task were used as indices of the efficiency of information processing that may mediate individual differences in intelligence. Results with 61 female college students contradict a pure speed of processing explanation of the relationship…

Various experiments demonstrated that the difficulty level of several performance-type intelligence test tasks is determined directly by stimulus and task variables that vary the information to be processed. The implications of these findings for intelligence and the problems of an experimental approach to the measurement of intelligence are…

A large sample of 11-year-olds were observed on a perceptual maze task. Three ability level groups were formed and compared as to overall response paths and specific binary decision configurations. Explanations for observed qualitative differences and discussion of the viability of the experimental approach adopted are presented. (Author/RD)

Demonstrated is a covariance principle that causes the observer to assume that if one aspect of a two-dimensional figure (its perimeter or its area) is conserved, the other aspect must also be conserved (pseudo-conservation). Mentally retarded individuals, assuming no such fixed relationship, correctly judged the changed state of the nonconserved…

Major visuospatial and verbal abilities were assessed for 197 10-year-olds in Hong Kong and 170 10-year-olds in the United Kingdom. The Hong Kong subjects resembled their Japanese counterparts in having high Searman's "g," exhibiting abstract reasoning ability, high spatial ability, high perceptual speed, and low word fluency. (SLD)