Measuring and Priming Underreporting Using the General Inventory of Behaviours, Symptoms, and Opinions (GIBSO)

Background: Underreporting impacts the self-reports’ validity across various domains (e.g., symptom and risk assessments). We evaluated the effectiveness of the General Inventory of Behaviours, Symptoms, and Opinions (GIBSO) in identifying underreporting. Method: Participants (N = 305), who participated in English or in Dutch, were told to respond honestly. Some participants (non-prime group, n = 76) received no further information, whereas others were primed to believe we would assess their ability to be care-takers (caretaker prime, n = 75), risk of endangering others (safety prime, n = 77), or developing substance-abuse issues (addiction prime, n = 77). All participants completed the GIBSO as well as mental and physical symptom inventories and questionnaires about drug use and aggression. Results: Groups had comparable scores on all inventories, indicating no significant impact of primes on participants’ responses. Both the GIBSO Total and General Underreporting (GU) subscale correlated significantly and negatively with other measures, and 28% of participants exceeded the GIBSO cutoff score (> 20). GIBSO Total and GU scale were equivalent between the international and Dutch participants, whereas Conservatism scale appeared more culturally sensitive. Conclusions: Given its negative correlations with symptom measures, the GIBSO, and particularly its GU subscale, holds promise as a screening tool for underreporting, although further systematic research is needed.