Spatial coupling affects both homologous and non-homologous limbs

The present study examined the interaction between limb movements in space. The amount of interaction was measured by how much moving one limb affected the movement of another limb. Participants were 24 right-handed university students (19 female, mean age=19 years). The task was to draw lines with the right hand while moving another limb in lines or circles of different sizes. Significant coupling effects were found between both homologous and non-homologous limbs. Movement of the right hand was most strongly affected by the left hand, less by the right foot, and least by the left foot, consistent with the functional cerebral distance model. This effect of limb was observed only in the major dimension along which movement was not restrained. Both the limb and dimension effects were reduced when the trajectory of motion decreased in size.