Digit Span, Forward and Backward: Separate and Unequal Components of the WAIS Digit Span

WAIS Digit Span scores of 50 subjects were evaluated to determine the relationship of Digits Forward and Digits Backward to intellectual functioning in an intellectually subnormal population. The subjects fell into one of five levels of intelligence, 50—59, 60—69, 70—79, 80—89, and 90—99, based upon Full Scale WAIS IQ. WAIS IQs and Digits Backward are significantly more highly correlated to all three WAIS IQs than are Digits Forward. Only the WAIS Digit Span (combined forward and backward) and Digits Backward discriminated across the five levels of intelligence.