Effects of model orientation on the visuomotor imitation of arm movements: the role of mental rotation.

An experiment was conducted to examine whether visual perspective has an effect on visuomotor imitation. The experiment presented varied visual perspectives in terms of spatial disparity between a model and an observer (model-observer-disparity) on six levels. Female participants were asked to imitate different arm movements presented in videos by animated models. These arm movements were elbow-extension-flexion movements with one (lower complexity) or three (higher complexity) reversals of movement direction. The results showed that model-observer-disparity affects spatial trajectories and velocities in the performance of motor imitations. The movements' complexity did not affect orientation dependence. Due to the non-linearity of the data, it is questionable if orientation dependence can be at least partially explained by mental rotation processes or differential ideomotor effects. According to these results, high model-observer-disparity should be avoided when using visual instructions in visuomotor imitation.