Psychometric Properties of the Reward Probability Index in a Mexican Sample

The psychometric properties of the Reward Probability Index (RPI), which assesses environmental reward as an indirect measure of response-contingent positive reinforcement (RCPR), were estimated in a Mexican population. With the voluntary participation of 1297 adults, reliability was assessed, and evidence was collected regarding the internal structure and its relationship with emotional symptomatology and other variables. Good internal consistency indices (ω and α) were found for both the total scale and its dimensions. A two-dimensional structure, comprising Reward Probability and Environmental Suppressors, and a second-order factor consistent with RCPR theory, was confirmed. This model demonstrated measurement invariance across sex, mental health treatment status, and the presence or absence of emotional symptomatology. Consistent relationships were observed between RPI scores and emotional symptomatology, psychological inflexibility, and life satisfaction. Additionally, evidence was found supporting the criterion validity of the RPI in relation to depression. RPI is a psychometrically solid instrument, and its use is recommended in the Mexican population to account for environmental reward, utilizing a total score and by dimensions.