Backward and forward serial recall across modalities: An individual differences perspective

The correlation between Digit Span Forward (DSF) and Digit Span Backward (DSB) scores from the Wechsler scales is moderate (r ≈.50), but surprisingly small given the highly similar nature of the tests. To-date, little research has examined the association between forward and backward recall across other stimulus modalities (e.g., words, shapes). Furthermore, some experimental research suggests that performance on verbal backward span may be affected differentially by visuospatial ability. Consequently, the purpose of this investigation was to evaluate the factorial validity of forward and backward span across three stimulus modalities: single digits, three-syllable words, and visual shapes. Additionally, a mental rotation test was administered to the participants (N = 211). Based on a factor analysis, four factors were identified: visuospatial memory span, three-syllable word span, DSF, and DSB. The DSF and DSB factors were related moderately at r =.40. Finally, visuospatial ability was not observed to relate to DSB uniquely (λ =.07; BF₀₁ = 8.65). The results suggest that there may be a process distinction that is unique to the recall of digits in forward and backward formats. However, the process distinction does not appear to be visuospatial ability.