0145-6008/88/ 1201-01 19%2.00/0 ALCOHOLISM: CLINICAL AND EXPERIMENTAL RFSEARCH Vol. 12, No. 1 January/February 1988 Motor Performance in Detoxified Alcoholics James L. York, PhD and Irving Biederman, PhD Detoxified male and female alcohdics (aged 20-49 years) and age- matched controls performed a series of 15-8ec target-tappingtasks in which they alternatively marked two target strips with a felt marker as rapidly and as accurately as possible. Consistentwith “Fitts’ Law” (Fitts PM: J Exp Psych 47981-391,1954), a highly linear relationship between movement time and task difficulty was observed in all four groups. Overall, the alcohdis were slower and made more errors than the controls, although the pattern of deficit differed for males and females. Accuracy, but not speed, was impaired in male alco- holics. The production of undershoot e m was increased more in akohdics than nonakoholicsin targets of narrower width, whereas the production of overshoot errors was increasedmore in alcoholics as target separation decreased. Female alcoholics displayed im- pairment in speed of movement, but not accuracy. However, both alcoholic groups displayedelevated error rates for the more difficult targets. It is thus possible that detoxified alcoholics might mimic the speed functions of nonalcoholic individuals at the occasional cost of an erroneous response at a difficult target. LCOHOLISM has been associated with dysfunction A in a variety of psychomotor and behavioral tasks.’,’ Performance deficits may persist for weeks, months, or years after alcohol use is discontinued. Recovery of func- tion with prolonged abstinence may be taken as strong evidence of the reversible toxic effects of alcohol. The persistence of deficits for long periods after abstinence may be related either to irreversible toxic effects of alcohol or to inherited deficiencies that may have antedated al- cohol use in alcoholic^.^ Only prospective studies are guaranteedto provide unambiguous answers to these ques- tions. However, more information is needed at this time in order to identify and categorize the deficits that are present in recovering alcoholics, thus providing a focus for prospective studies. Although neuropsychological performance has been ex- tensively studied in alcoholics, only a few studies have addressed the specific impact of alcoholism on related motor movement control functions, despite the implica- tions of this research for occupational functioning, as well as for treatment and rehabilitation programming. One noteworthy study demonstrated that detoxified alcoholics were deficient in their ability to modulate the speed at which they turned a knob when instructed to turn it as slowly as possible? A deficit in motor inhibitory control functions was suggested by the authors as one possible From the Division ofAIcoholismand Alcohol Abuse, Research Institute on Alcoholism and Department of Psychology, State University of New York at Buffalo. Receivedfor publication February 2, 1987; revised manuscript received April 22, 1987; accepted June 22, 1987. Reprint requests: James L. York, Research Institute on Alcoholism, 1021 Main Street, Buffalo,NY 14203. Copyright 0 1988 by The Research Society on Alcoholism. explanation for the performance of alcoholic subjects. This deficit is considered to be distinct from the lack of behav- ioral inhibitory control reported in alcoholic^.^ Little re- search has been performed to further probe and extend these original and provocative observations and to further define the meaning of “motor inhibitory control.” Notably lacking is information with regard to the per- sisting effect of excessive alcohol intake on fine movement functions of the hands. In normal subjects, hand move- ment speed has been found to be linearly related to target difficulty when small amplitude movements of the hand are used in a reciprocal tapping task. This relationship, known as “Fitts’ Law,”7may be summarized by the equa- tion: 20 Movement time = a + b log, - W where a and b are constants and D and W refer to movement distance and target width, respectively. The expression was defined by Fitts7 as the “index of difficulty” (ID), or the difficulty encountered in making a quick hit on a target. Fitts’ Law has been found to accurately describe hand motor control functions across a broad age range in normal males and females7 An attractive feature of Fitts’ task is that it involves the type of visually guided motor response that is a critical component of a wide variety of everyday work- and recreation-related skills.6 The purpose of the present study was to determine if the information processing characteristics of the motor system (as assessed by Fitts’ Task) in alcoholics obeys the same principles that apply to normal subjects. In particu- lar, Fitts’ Task allows for the determination of speed-for- accuracy tradeoffs which may be deficient in alcoholics and may reflect disrupted inhibitory motor control func- tions. Inasmuch as some of the health consequences of alcoholism may be gender specific, both male and female subjects were examined in this study. METHODOLOGY Subjects and Procedure Male and female subjects (ages, 20-49 years) were recruited From the general population (nonalcoholics) and from three local alcoholism treatment programs. The three programs included a state-operated, a county-operated and a privately operated unit. Although data on socio- economic status were not collected,control subjectswere usually working class individuals recruited from the staff of the Research Institute on Alcoholism and neighboring office buildings. Subjects in treatment pro-