During different sports and activities of daily living, individuals often perform tasks that require the simultaneous upper and lower limb activity. How does the concurrent production of one motor task influence the other? Traditionally, researchers have looked at time-sharing using a dual task paradigm, grading both primary and secondary tasks on degree of attentional capacity, and looking for interference between tasks. To date, the effects of time-sharing in a dual motor task have not been investigated. The purpose of this research is to investigate the effect of a simultaneously produced motor task (clapping) on gait parameters (control variables and order parameters) in walking and interpret the results using a traditional and dynamical systems framework. 60 participants in 5 age groups (4, 6, 8, 10, adult) performed 3 trials of walking alone, and of simultaneous clapping and walking. Independent measures were age group and task. Dependent measures classified as either control variables (step time, step length, and velocity) or order parameters (mean temporal phasing, mean amplitude phasing). Each of these measures was analyzed separately using 5 (age) x 2 (task) ANOVA with repeated measures on the second factor. For the order parameters, significant differences existed between tasks in the mean temporal phasing (F (1,55) = 4.07, p<.05), but not mean amplitude phasing . For the control variables, statistical analyses revealed significant main effects for task (velocity (F (1,55)=47.55, p<.0001); step time (F(1,55)=35.37, p<.0001); step length (F(1,55)=21.14, p<.0001)) and age group (velocity (F(4,55)=3.30, p=.017); step time (F(4,55)=7.48, p<.0001); step length (F(4,55)=26.21,p<.0001)) for all three control variables. No age x task interaction was found. In fact, the task related differences in control variables remained remarkably consistent across all age groups. The results are surprising when interpreted from a traditional time-sharing perspective; although the paradigm was not a traditional dual task, one would expect that the simultaneous performance of two well-learned motor task with no temporal conflicts would not affect gait characteristics due to low processing requirements. Additionally, any interference should decrease as a function of age. These results are more easily explained using a coupled oscillator model, which suggests that the limbs entrain to each other in the dual motor task condition. This suggests that the dual motor condition is not simply the combination of two unrelated tasks, but rather the production of a novel, four limb task. Research supported by the University of Delaware Research Foundation.Keyword(s): research