Effects of increased complexity of visuo-motor transformations on children's arm movements.

The effects of increasing complexity of visuo-motor transformations on movement were examined in 4-, 6-, and 8-year-old children and adults. Participants performed a 'center-out' drawing task under three increasingly complex conditions: (1) Normal transformation: The target, line path and hand position were fully visible, in the horizontal plane, throughout the movement. (2) Aligned transformation: The target and line path were displayed horizontally above the workspace, with vision of the arm/hand occluded. (3) Vertical transformation: The target and line paths were presented on a vertical computer monitor with vision of the arm/hand occluded. Results showed that with increasing age, movements became faster, straighter, and smoother. The 4- and 6-year-old children were more variable in their specification of movement direction than the 8-year-old children and the adults, and were also more affected by the complexity of the transformation. This suggested that besides the complexity of the visual transformation, the familiarity/experienced environment might also play a role in 'sharpening' the transformation maps represented in movement planning.