EXPLORING INTERLIMB CONSTRAINTS DURING BIMANUAL GRAPHIC PERFORMANCE -EFFECTS OF MUSCLE GROUPING AND DIRECTION

Past studies on bimanual coordination have revealed a general preferen ce to move the limbs in a symmetrical fashion, also denoted as the in- phase mode. Its counterpart, the asymmetrical or anti-phase mode, is p erformed with lower degrees of accuracy and stability. This ubiquitous tendency to activate the homologous muscle groups is referred to as t he muscle grouping constraint (egocentric constraint). The present stu dy confirmed the generalizability of this constraint across various co ordination patterns, performed in the horizontal plane. In addition, e vidence was generated that movement direction in extrinsic space also constrains bimanual coordination (allocentric constraint). Overall, th e present observations suggest that direction is an important movement parameter that is encoded in the central nervous system and that is s ubject to interactions between the neural specifications of both limbs . (C) 1998 Elsevier Science B.V.