Accuracy in the frequency accrual speed test (fast), inspection time and psychometric intelligence in a sample of primary school children

This study tested 28 primary school children, using six subtests of the WISC-R, an inspection time (IT) task, and a frequency accrual speed test (FAST) procedure, proposed by Vickers (Personality and Individual Differences, 19, 863–879, 1995) as a measure of mental speed. Performance in the FAST task was stable and reliable across sessions, and showed good correlations with full-scale IQ, both overall and for each session. Contrary to a simple mental speed assumption, however, the data showed clear recency effects. Estimates of IT, averaged over sessions, showed a moderate correlation with IQ, but decreased significantly and showed only low reliability across sessions. The latter result appeared to be due to an increase over sessions in the use of apparent movement strategies. Subjects who did not use an apparent movement strategy showed higher IT-IQ correlations. Although FAST and IT scores were not correlated for the group as a whole, when strategy users were excluded the FAST-IT correlation was significant for session 1. The results are discussed in terms of alternative interpretations of accuracy in the FAST task as a measure of mental speed, as determined by retroactive stimulus attenuation and as an index of working-memory capacity.