90 Cognitive Success in the Setting of Performance Validity Failure

Abstract

Objective:

Although studies have shown unique variance contributions from performance invalidity, it is difficult to interpret the meaning of cognitive data in the setting of failed performance validity tests (PVT). Furthermore, a clearer understanding of the clinical utility of cognitive data in the context of invalid PVTs is necessary to inform decisions about battery length once PVTs are failed. The primary aim of the current study is to broadly describe cognitive outcomes in the setting of PVT failure.

Participants and Methods:

Two hundred and twenty-two veterans with a history of mild traumatic brain injury referred for clinical evaluation completed cognitive and performance validity measures. Standardized scores were characterized as Within Normal Limits and Below Normal Limits at the normative 16th percentile and number of Within Normal Limits scores were calculated for each participant. Cognitive outcomes are described across four commonly used PVTs. Rates of below normal limits cognitive performance, and PVT failure were assessed via student’s t tests among participants who were classified as productive or unproductive based on involvement in work and/or school.

Results:

Among participants who performed in the invalid range on TOMM trial 1, 36-81% of cognitive data reflected within normal limits performance. Similarly, 47-81% of those who demonstrated performance invalidity based on the Word Memory Test (WMT) earned broadly within normal limits scores across cognitive testing. For those with invalid performance based on the normative digit span scaled score, 35-88% of cognitive data was at or above the 16th percentile. Within normal limits across cognitive tests ranged from 16-71% when the California Verbal Learning Test-Second Edition forced choice was used as an indicator of performance validity. In the context of PVT failure, the average number of cognitive performances below the 16th percentile ranged from 5-7 of 14 tasks depending on which PVT measure was applied. Within the total sample, there were no differences in the total number of below normal limits performances on cognitive measures between productive and unproductive participants (T = 1.65, p = 1.00). Additionally, there were no differences in the total number of PVTs failed between the productive and unproductive groups (T = 0.33, p = 0.743).

Conclusions:

Results of the current study suggest that the range of within normal limits cognitive performance in the context of failed performance validity measures varies greatly. Importantly, findings indicate that neurocognitive data may still provide important practical information regarding cognitive abilities (i.e., that test takers can oftentimes perform within broadly normal limits on many cognitive tasks), despite poor PVT outcomes. Further, given that neither rates of below normal limits cognitive performance nor rates of PVT failures differed among productivity groups, results have important implications for decisions to continue testing and recommendations in a clinical setting.