Precise movements in awkward postures: A direct test of the precision hypothesis of the end-state comfort effect

When humans manipulate an object, they prefer to grasp the object in a way that allows to terminate the manipulation in a comfortable posture. The reasons for this end-state comfort effect have remained elusive so far. One explanation assumes that comfortable end-states are not preferred per se, but rather because they come with increased movement precision, which is typically required by the end of an object manipulation. Five experiments were conducted to test this hypothesis and yielded 3 main results. First, grasps that increase control over an object are preferred irrespective of the resulting arm postures. Second, differences in the controllability associated with comfortable and uncomfortable postures are sufficient to elicit the end-state comfort effect. Third, grasps that optimize control are preferred even when this implies adopting uncomfortable end-states. Altogether, these findings directly support the hypothesis that the end-state comfort emerges because it maximizes the control over the manipulated object at the end of object manipulations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).