SEQUENTIAL AND COORDINATIVE COMPLEXITY IN TIME-ACCURACY FUNCTIONS FORMENTAL ARITHMETIC

Time-accuracy functions for tasks involving single-digit mental additi on and subtraction were derived in a sample of 18 younger (mean age = 21.7 years) and 16 older adults (mean age = 68.8 years). Sequential co mplexity was manipulated by varying the number of operations (5 vs. 10 ); coordinative complexity was induced by bracketing. Age differences were apparent in the coordinative conditions, even though no age diffe rence was present in the sequential conditions. This indicates that th e age difference under conditions of high coordinative demands could n ot be attributed solely to a decline in basic speed of processing. The Age x Complexity interaction was due to larger onset times and lower asymptotic performance by the older adults in the coordinative conditi ons but not due to to rate of approach to the asymptote. This implies that coordinative demands do not differentially hurt access from seman tic memory in older adults; however, coordinative demands do have disp roportionately negative consequences for computation speed and self-mo nitoring in elder adults.