The abilities to attribute an action to its proper agent and to understand its meaning when it is produced by someone else are basic aspects of human social communication. Several psychiatric syndromes, such as schizophrenia, seem to lead to a dysfunction of the awareness of one’s own action as well as of recognition of actions performed by other. Such syndromes offer a framework for studying the determinants of agency, the ability to correctly attribute actions to their veridical source. Thirty normal (...) subjects and 30 schizophrenic patients with and without hallucinations and/or delusional experiences were required to execute simple finger and wrist movements, without direct visual control of their hand. The image of either their own hand or an alien hand executing the same or a different movement was presented on a TV-screen in real time. The task for the subjects was to discriminate whether the hand presented on the screen was their own or not. Hallucinating and deluded schizophrenic patients were more impaired in discriminating their own hand from the alien one than the non-hallucinating ones, and tended to misattribute the alien hand to themselves. Results are discussed according to a model of action control. A tentative description of the mechanisms leading to action consciousness is proposed. (shrink)

We tested the hypothesis that our ability to detect fine kinematics variations is tuned to reveal more subtle differences when the motion pattern belongs to the observer compared to another individual. To this purpose, we analyzed the responses of 15 subjects in a same-different task on pairs of movements, which could belong to one or two different subjects. Self vs. Other comparisons were obtained by presenting both the observer’s and another participant’s kinematics. Subjects responded faster and more accurately when they (...) observed their own gestures compared to movements of another participant. In the latter case, slight kinematic differences were more likely to remain undetected. These findings are discussed within an ecological framework: in observing others, we are more concerned with detection of goals and intentions, i.e., outstanding variations in motion patterns. Conversely, in self-observation detection of more subtle differences is required to facilitate learning and optimization of motor acts. (shrink)

High-spin states have been studied in Pr-135(59), populated through the Cd-116(Na-23,4n) reaction at 115 MeV, using the Gammasphere gamma-ray spectrometer. The negative-parity yrast band has been significantly extended to spin similar to 45 (h) over bar and excitation energy 21.5 MeV, showing evidence for several rotational alignments. The positive-parity yrast band of Ce-135(58), populated through the p4n channel of this reaction, was also populated to spin similar to 38 (h) over bar and excitation energy 18 MeV. Cranking calculations indicate that (...) these nuclei are soft with respect to the triaxiality parameter gamma and that several competing nuclear shapes occur at high spin. (shrink)