Sequential and coordinative complexity: age-based processing limitations in figural transformations.

Dimensions of cognitive complexity in figural transformations were examined in the context of adult age differences. Sequential complexity was manipulated through figural transformations of single objects in a multiple-object array. Coordinative complexity was induced through spatial or nonspatial transformations of the entire array. Results confirmed the prediction that age-related slowing is larger in coordinative complexity than in sequential complexity conditions. The effect was stable across 8 sessions (Experiment 1), was obtained when age groups were equated in accuracy with criterion-referenced testing (Experiment 2), and was corroborated by age-differential probabilities of error types (Experiments 1 and 2). A model is proposed attributing age effects under coordinative complexity to 2 factors: (a) basic-level slowing and (b) time-consuming reiterations through the processing sequence due to age-related working memory failures.