Thai adaptation and reliability of three versions of the Barratt Impulsiveness Scale (BIS 11, BIS-15, and BIS-Brief).

Long, short, and brief versions of the Barratt Impulsiveness scale (BIS-11, BIS-15, and BIS-Brief) were tested in an adult Thai population. The BIS-11T and BIS-15T were translated, back-translated, and administered to a non-clinical population (n = 305) of native Thai speakers who returned 2 weeks later for re-test. BIS-Brief-T psychometrics were calculated post-hoc. Impulsivity scores were normally distributed for the BIS-11T and BIS-15T, but not BIS-Brief-T. Excellent internal consistency was observed, with Cronbach's alpha coefficients above 0.80 for all translated instruments: BIS-11T (α = 0.86), BIS-15T (α = 0.81), BIS-Brief-T (α = 0.81). A total of 260 participants completed both instruments (85%), with test-retest reliability exceeding r = 0.81. All three instruments were highly correlated (r = 0.83-0.89). Confirmatory factor analysis supports a three factor structure (attention, motor, non-planning) for BIS-15T and two factor structure for BIS-11T. BIS scales can support measurement of a range of impulsivity scores in an adult Thai population, though predictive validity of these scales remains unexplored.