Establishing stable test performance in tests from the Behavioral Assessment and Research System (BARS)

Research to identify adverse effects in humans chronically exposed to neuro toxic substances in the workplace or environment typically assesses people at one point in time in a cross-sectional study. The most widely used strat egy employs performance measures taken from a single point in time and comp ares these with either performance of a control group or established normat ive data. However, multiple comparison points of the same people on the sam e test allow the dissection of acute - from chronic - exposure effects, amo ng other important questions. When performance measures are used from multi ple points in time, within-subject deviations are examined. For either rese arch design, the goal is to minimize the effects of practice and to obtain stable performance on a test. Demographic variables such as age, education, and cultural background or ethnicity influence performance on neurobehavio ral tests. These variables may also influence the development of stable per formance. Different populations may have different learning curves so that stable performance on a test is achieved with different amounts of practice . This is especially important when making comparisons across groups that m ay not have equivalent backgrounds. The performance of three groups, Englis h-speaking adults, Spanish-speaking adolescents, and Spanish-speaking migra nt adolescents, was examined. Each group completed a battery of neurobehavi oral tests from the Behavioral Assessment and Research System (BARS) during four sessions. Repeated measures ANOVAs were used to investigate performan ce across time. Tests measuring motor performance produced stable performan ce from the first session. More complex tasks that involved attention and m emory showed a practice effect across sessions. (C) 2000 Intox Press, Inc.