Sequential and coordinative processing dynamics in figural transformations across the life span

This work tests the proposition that two distinct factors involved in life span cognitive development are mental speed and coordination efficiency. Dynamics of information processing in a figural transformation task were assessed via time-accuracy functions for children (mean age = 9.5 years), young adults (mean age = 23.7 years), and old adults (mean age = 73.7 years). Corresponding to the two proposed factors, speed and coordination, both sequential and coordinative aspects of complexity were varied. Sequential complexity was manipulated through the number of objects to be checked for transformations; coordinative complexity was manipulated through the number of transformations to be considered simultaneously. Individual time--accuracy operating characteristics were adequately described by exponential functions for all age and complexity levels. Complexity-specific effects confirmed the general expectation of a particularly large age sensitivity of coordinative functions. Proportional adult age effects in the processing time parameter were larger for coordinatively complex than for sequentially complex conditions. For the contrast between children and young adults this was the case only for high coordinative complexity. Results are interpreted in terms of (a) dissociable developmental changes in speed of processing and working memory functioning across the life span and (b) differential effects of coordinative demands in children and old adults.