What Makes a Baseline Test 'Invalid' — and What to Do About It

ImPACT and other computerized neurocognitive tests include embedded validity indicators designed to detect unreliable baseline performances. Understanding these indicators — and knowing what to do when a baseline is flagged — is essential for anyone managing a baseline testing program.

What the validity indicators catch

ImPACT’s validity indicators flag patterns consistent with: extremely slow processing speed (suggesting the athlete wasn’t trying or was severely distracted), unusually fast reaction time with poor accuracy (suggesting random clicking), scores that fall below statistically improbable thresholds, and inconsistency patterns within subtests. The Impulse Control composite score, derived from the Color Match module, is particularly sensitive to response validity — it measures whether the athlete is responding thoughtfully or just clicking impulsively.

The research

Research by Schatz, Moser, and colleagues, published in Applied Neuropsychology: Child (2019) and the Archives of Clinical Neuropsychology, confirmed that invalid baseline performance on ImPACT occurs at meaningful rates in high school populations. A study published in the Clinical Journal of Sport Medicine (Szabo et al., 2022) examining two years of collegiate baseline data found that retesting athletes with initially invalid baselines produced significantly improved scores on all composites — confirming that the original invalid result was caused by poor testing conditions or low effort, not cognitive impairment.

Why invalid is worse than nothing

An invalid baseline is worse than no baseline. If an athlete sandbagged or was distracted during their baseline, their artificially low “healthy” scores become the comparison point. After a real concussion, their post-injury scores might actually appear better than baseline — potentially leading to premature clearance of a genuinely impaired athlete. This is the most dangerous scenario in baseline-guided concussion management. See also sandbagging.

The solution

The solution is straightforward: re-test. Any baseline flagged by validity indicators should be re-administered under improved conditions — quieter environment, smaller group, better supervision, athlete education about the importance of effort. At Headquarters, every baseline is reviewed for validity before being finalized, and flagged results trigger mandatory re-testing.

Frequently asked questions