One-month test-retest reliability of the ImPACT test battery.

In order to better understand the test-retest reliability of the ImPACT test battery, 25 undergraduate students completed two ImPACT tests across a time frame of 4 weeks between assessments. Participants had not previously completed ImPACT and had no history of concussion. Pearson's correlation coefficients (r) and intraclass correlation coefficients (ICCs) were as follows: Verbal Memory = .66/.79 (r/ICC), Visual Memory = .43/.60, Visual Motor Speed = .78/.88, Reaction Time = .63/.77, and Total Symptoms = .75/.81. Dependent sample t-tests revealed significant improvement on only Visual Motor Speed composite scores. Reliable Change Indices showed a significant number of participants fell outside 80% and 95% confidence intervals for only Visual Motor Speed scores (but no other indices), whereas all scores were within 80% and 95% confidence intervals using regression-based measures. Results suggest that repeated exposure to the ImPACT test may result in significant improvements in the physical mechanics of how college students interact with the test (e.g., performance on Visual Motor Speed), but repeated exposure across 1 month does not result in practice effects in memory performance or reaction time.