Action simulation for others is not constrained by one's own postures

Does the brain use the same mechanism to simulate both our own and other persons' actions? If it does, then one's current posture should influence action simulation for others, depending on whether current and imagined postures differ. To test this prediction, 20 observers sat upright or bent forward while evaluating the reaching range of a model that had been photographed in similar postures. Posture congruency did not influence performance but decisions were faster and more accurate when the simulation required fewer posture changes. These results begin to reveal the processes that transform visual inputs into motor predictions for others. Implications of the present findings for our understanding of the so-called mirror system are discussed. (C) 2004 Elsevier Ltd. All rights reserved.