Delayed motor production of open polygonal chains presented visually in static and dynamic modes: Comparison between 9- to 11-year-old children and adults

Production of drawing movements was studied in 29 right-handed children aged 9 to 11 years. The movements were sequences of horizontal and vertical linear strokes conjoined at a right angle (open polygonal chains) referred to below as trajectories. Trajectories comprising four to six segments were presented to a subject visually in a static or dynamic mode (i.e., as a linear drawing or as a moving cursor leaving no trace). The subjects were asked to draw (copy) the trajectory as fast as possible without lifting the pen in response to a delayed go-signal (short click). The parameters analyzed were the production latency time, the average duration of movement along a trajectory segment, and the overall number of errors made by a subject while producing the trajectory. Comparison of the data obtained in children with similar data for adults (16 subjects) revealed the following patterns. First, between the ages of 9 and 11 years, the error rate rapidly decreased for both the static and the dynamic modes of presentation, although 11-year-old children still made more errors than adults. Second, the average movement duration shortened with age, while the latency time tended to increase. Third, in 9- to 11-year-old children, in contrast to adults, the latency times for the static and dynamic modes of trajectory presentation did not differ from each other. The differences in trajectory production between adults and children are attributed to the predominant involvement of on-line programming in children and preprogramming in adults. © 2015, Pleiades Publishing, Inc.