Base rates of non-credible performance in a post-secondary student sample seeking accessibility accommodations

Objective: Performance Validity Tests (PVTs) have been used to identify non-credible performance in clinical, medicolegal, forensic, and, more recently, academic settings. The inclusion of PVTs when administering psychoeducational assessments is essential given that specific accommodation such as flexible deadlines and increased writing time can provide an external incentive for students without disabilities to feign symptoms. Method: The present study used archival data to establish base rates of non-credible performance in a sample of post-secondary students (n = 1045) who underwent a comprehensive psychoeducational evaluation for the purposes of obtaining academic accommodations. In accordance with current guidelines, non-credible performance was determined by failure on two or more freestanding or embedded PVTs. Results: 9.4% of participants failed at least two of the PVTs they were administered, of which 8.5% failed two PVTs, and approximately 1% failed three PVTs. Base rates of failure for specific PVTs ranged from 25% (b Test) to 11.2% (TOVA). Conclusions: The present study found a lower base rate of non-credible performance than previously observed in comparable populations. This likely reflects the utilization of conservative criteria in detecting non-credible performance to avoid false positives. By contrast, inconsistent base rates previously found in the literature may reflect inconsistent methodologies. These results further emphasize the importance of administering multiple PVTs during psychoeducational assessments. The implications of these findings can further inform clinicians administering assessments in academic settings and aid in the appropriate utilization of PVTs in psychoeducational evaluation to determine accessibility accommodations.