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Asymmetrical hand function was examined in the context of expert sports performance: hitting in professional baseball. An archival study was conducted to examine the batting performance of all Major League Baseball players from 1871 to 1992, focusing on those who batted left (n = 1,059) to neutralize the game asymmetry. Among them, left-handers (n = 421) were more likely to hit with power and to strike out than right-handers (n = 638). One possible account, based on the idea of hand dominance and an analogy to tennis, is that batting left involves a double-handed forehand for left-handers and a weaker and more reliable double-handed backhand for right-handers. The results are also interpretable in the light of Y. Guiard's (1987) kinematic chain model of a between-hands asymmetrical division of labor, which provides a detailed account of why left batting is optimal for left-handers.

Asymmetrical hand function was examined in the context of expert sports performance: hitting in professional baseball. An archival study was conducted to examine the batting performance of all Major League Baseball players from 1871 to 1992, focusing on those who batted left (n = 1,059) to neutralize the game asymmetry. Among them, left-handers (n = 421) were more likely to hit with power and to strike out than right-handers (n = 638). One possible account, based on the idea of hand dominance and an analogy to tennis, is that batting left involves a double-handed forehand for left-handers and a weaker and more reliable double-handed backhand for right-handers. The results are also interpretable in the light of Y. Guiard's (1987) kinematic chain model of a between-hands asymmetrical division of labor, which provides a detailed account of why left batting is optimal for left-handers.

Two experiments examined the variance associated with the motor component in a time production task involving a series of finger taps. Use of the segmentation strategy described by Grondin (1992) allowed the isolation of a part of the variance associated with the motor component in such a tapping task. It is shown that replacing a finger tap by an internal indicator reduces the coefficient of variation by about .5% per second. As well, these experiments showed that the choice of subintervals, when an interval is segmented during a timing task, is a major source of variance. It is concluded that the segmentation strategy provides a general framework for analyzing the part of the variability provoked by each of two components -- the clock and the motor system -- involved in a time interval production task.

Intermittent bursts of weak magnetic fields whose patterns simulate normal amygdaloidal-hippocampal activity were generated by computer over the right or left temporal regions of men and women during partial sensory deprivation. As predicted, women but not men reported greater apprehension during right-hemispheric but not left-hemispheric stimulation. Intrusions of right-hemispheric processes have been hypothesized to affect self-esteem adversely. These results also support the role of the right parahippocampal region in the production of panic attacks.