Arm folding, hand clasping, and Luria's concept of “latent left-handedness”

Abstract

Luria (1947/1970) proposed left-top positions in arm folding (AF) and hand clasping (HC) to be signs of “latent left-handedness”. However, research since has revealed that (1) left-top positions are canonical for European right-handers and (2) combined AF/HC measures may provide more information about cerebral laterality than either measure considered alone. We tested whether AF and HC or AF/HC combinations predicted diminished right-handedness for 12 handedness items. Results from 509 healthy participants showed that (1) left-top positions in AF and HC were dominant across participants, as was right-handedness, and a right-top position in HC was associated with attenuated right-handedness, (2) right-hand preference was more frequently associated with congruent AF/HC combinations, especially of the LL type (AF: left-top / HC: left-top), and (3) non-right-hand preference was associated with non-congruent, predominantly LR combinations. We conjecture that the LL type combination indicates left hemispheric dominance for motor actions, whereas the LR combination, in which HC as the distally innervated posture deviates from the canonical pattern, indicates attenuated hemispheric asymmetry. Our data support Luria's proposition that a left-top preference in AF points to “latent” left-handedness, but only if associated with a right-top preference in HC. Consistent left-top preference for the combined AF/HC measure appears to predict right-handedness.