Hand Movement Speed and Accuracy in Detoxified Alcoholics

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Abstract
Detoxified alcoholics (n = 192) were found to be 9.3% slower than age-matched controls (n = 112) with regard to the composite speed (movement time, MT) with which they were able to strike targets of various sizes and distances with a hand-held stylus at onset of a light stimulus (Fitts's Task). Females (n = 102) were 8% slower than males (n = 202), and blacks (n = 103) about 15.6% slower than whites (n = 201). Gender was the only significant factor with regard to errors (target misses), with women committing 28% fewer errors than men. Women, in contrast to men, appear to trade speed for accuracy in this task. Favorable socioeconomic/medical status and target misses were directly related to movement speed. Thus, when the MT data were corrected for lifestyle variables, the significance of the alcohol effects on MT disappeared, but gender differences persisted. The alcohol effect became statistically significant, the ethnic group differences remained statistically significant, and the gender effect became insignificant when MT scores were corrected for accuracy of performance (target misses). The slope of the linear function relating MT to target difficulty was similar for all subgroups. Prior knowledge of the direction of movement was found to affect MT performance more in white than in black subjects. With regard to reaction times, ethnic group and alcohol use effects remained statistically significant after corrections for lifestyle and errors were made, with values for blacks about 5% slower than values for whites, and values for alcoholics about 4.6% slower than those for controls. Prior knowledge of the direction of movement significantly improved (shortened) reaction time in all subgroups (14%-19%).

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