A biaxial electrogoniometer (Model SG 110, Biometrics; Gwent, UK) was used to measure adduction/abduction i.e. palmarabduction (Greene and Heckman, 1994) and flexion/extension of the thumb. The endblocks of the goniometer were applied on the dorsal side of the proximal phalange on the right thumb and on the medial aspect of the radius just proximal to the wrist joint (Fig. 1). Both goniometer endblocks were rigidly secured to the subject’s wrist and thumb using double-sided tape. The thumb’s general orientation was considered as the orientation of the proximal phalang