How Plausible Is the Implausible? Students' Plausibility and Prevalence Ratings of the Self-Report Symptom Inventory

Some self-report symptom validity tests, such as the Self-Report Symptom Inventory (SRSI), rely on a detection strategy that uses bizarre, extreme, or very rare symptoms. Thus, items are constructed to invite respondents with an invalid response style to affirm pseudosymptoms that are usually not experienced by genuine patients. However, these pseudosymptoms should not be easily recognizable, because otherwise sophisticated over-reporters could strategically avoid them and go undetected. Therefore, we tested how well future psychology professionals were able to differentiate between genuine complaints and pseudosymptoms in terms of their plausibility and prevalence. Psychology students (N = 87) received the items of the SRSI online and were given the task to rate each item as to its plausibility and prevalence in the community. Students evaluated genuine symptoms as significantly more plausible and more prevalent than pseudosymptoms. However, 56% of students rated pseudosymptoms as moderately plausible, whereas 17% rated them as moderately prevalent in the general public. Overall, it appears that psychology students are successful in distinguishing bizarre, unusual, or rare symptoms from genuine complaints. Yet, the majority of students still attributed relatively high prima facie plausibility to pseudosymptoms. We contend that if such a trusting attitude is true for psychology students, it may also be the case for young psychology practitioners, which, consequently, may diminish the probability of employing self-report validity measures in psychological assessments.