Forward and backward digit span interaction with race and IQ: predictions from Jensen's theory.

From Jensen's two-level theory of mental abilities (Level I: rote learning and memory, involving little or no transformation of the input; Level II: complex cognitive processing involving transformation and mental manipulation of input) it was predicted that forward digit span (FDS) should correlate less with IQ than backward digit span (BDS), and age and race should interact with FDS-BDS, with the FDS-BDS difference decreasing as a junction of age and a greater White-Black difference in BDS than in FDS. The predictions were substantiated at a high level of significance in large representative samples of White and Black children of ages 5 to 12 years, who were given the Wechsler Intelligence Scale for Children (Revised). Supplementary studies found no support for rival hypotheses based on anxiety, task difficulty, and race of