Interplay of Biomechanical Constraints and Kinematic Strategies in Selecting Arm Postures

In this study, the authors examined the interplay between biomechanics and control strategies in the resolution of excess degrees of freedom at the joint level. Seven participants made aimed arm movements from 30 starting points and several starting postures to targets. Final arm postures for movements to a target exhibited substantial joint angle variation. Through regression modeling and by comparing observed final arm postures with biomechanically plausible postures, the authors identified 3 kinematic strategies: (a) Maintain deviations from the average angle at the starting point to the joint's final posture; (b) make torso rotations that are a fixed proportion of shoulder rotations; and (c) adopt a characteristic combination of 4 wrist-positioning approaches. The results demonstrated that kinematic strategies can account for substantial variance in final arm postures, if one takes into account 2 types of individual differences—those that arise inevitably from biomechanical constraints and those that reflect choices in movement strategy.     

Guest Editorial: Who's Afraid of Life After Death?

The evidence for an afterlife is sufficiently strong and compelling that an unbiased person ought to conclude that materialism is a false theory. Yet the academy refuses to examine the evidence, and clings to materialism as if it were a priori true, instead of a posteriori false. I suggest several explanations for the monumental failure of curiosity on the part of academia. First, there is deep confusion between the concepts of evidence and proof. Second, materialism functions as a powerful paradigm that structures the shape of scientific explanations, but is not itself open to question. The third explanation is intellectual arrogance, as the possible existence of disembodied intelligence threatens the materialistic belief that the educated human brain is the highest form of intelligence in existence. Finally, there is a social taboo against belief in an afterlife, as our whole way of life is predicated on materialism and might collapse if near-death experiences, particularly the life review, were accepted as fact.