Normal cognitive test scores cannot be interpreted as accurate measures of ability in the context of failed performance validity testing: A symptom- and detection-coached simulation study

Abstract

Introduction: While use of performance validity tests (PVTs) has become a standard of practice in neuropsychology, there are differing opinions regarding whether to interpret cognitive test data when standard scores fall within normal limits despite PVTs being failed. This study is the first to empirically determine whether normal cognitive test scores underrepresent functioning when PVTs are failed.

Method: Participants, randomly assigned to either a simulated malingering group (n = 50) instructed to mildly suppress test performances or a best-effort/control group (n = 50), completed neuropsychological tests which included the North American Adult Reading Test (NAART), California Verbal Learning Test – 2nd Edition (CVLT-II), and Test of Memory Malingering (TOMM).

Results: Groups were not significantly different in age, sex, education, or NAART predicted intellectual ability, but simulators performed significantly worse than controls on the TOMM, CVLT-II Forced Choice Recognition, and CVLT-II Short Delay Free Recall. The groups did not significantly differ on other examined CVLT-II measures. Of simulators who failed validity testing, 36% scored no worse than average and 73% scored no worse than low average on any of the examined CVLT-II indices.

Conclusions: Of simulated malingerers who failed validity testing, nearly three-fourths were able to produce cognitive test scores that were within normal limits, which indicates that normal cognitive performances cannot be interpreted as accurately reflecting an individual’s capabilities when obtained in the presence of validity test failure. At the same time, only 2 of 50 simulators were successful in passing validity testing while scoring within an impaired range on cognitive testing. This latter finding indicates that successfully feigning cognitive deficits is difficult when PVTs are utilized within the examination.