Dorien Bangma

FDM AND CURRENT SYMPTOMS OF ADHD | 189 Materials ADHD rating scale. The ARS is a self-report questionnaire that was used to evaluate current and retrospective symptoms of ADHD (Kooij et al., 2005, 2008). The ARS was originally developed on the basis of the DSM-IV, however, can also be used with the current criteria as defined by the DSM-5 (American Psychiatric Association, 2013). Both the versions for current and retrospective symptoms of the ARS have 23 items evaluating 18 symptoms of ADHD. On a four-point scale (0 = ‘rarely or never’ , 1 = ‘sometimes’ , 2 = ‘often’ and 3 = ‘very often’ ), participants had to indicate for each item which answer alternative described their behavior best in the past six months (i.e., current symptoms) or during childhood when being 0 – 12 years old (i.e., retrospective symptoms). Using the scoring system of Kooij et al. (2005), an ADHD symptom was classified as present when ‘often’ or ‘very often’ was answered on an item. Five criteria of ADHD as described in the DSM-5 (i.e., criteria 1a, 1d, 2a, 2d and 2e) were each represented by two items of the ARS and were classified as present when ‘often’ or ‘very often’ was answered on at least one of the two items. Total scores can be calculated based on all 23 items for both the current and retrospective version of the ARS. Furthermore, for each version, total scores can be calculated based on items representing symptoms of inattention (total of 11 items, Cronbach’s alpha = .86) and hyperactivity/impulsivity symptoms (total of 12 items, Cronbach’s alpha = .81; Kooij et al., 2008). Higher scores are indicative of more (severe) symptoms of ADHD. Impulsive buying questionnaire. The Impulsive Buying Questionnaire (IBQ) consists of 31 items focused on the tendency to buy on impulse (Bangma et al., 2017, 2019). Participants have to indicate on a four-point Likert scale (ranging from 1 = ‘strongly disagree’ to 4 = ‘strongly agree’ ) whether they agree with the statements. Three components of impulsive buying can be evaluated based on the sum of specific items; a cognitive component (i.e., the thoughts and urge to buy on impulse; 15 items; e.g., ‘When I go shopping, I buy things that I did not intend to purchase’ ; Cronbach’s alpha = .80), an affective component (i.e., the emotions and feelings that lead to impulsive behavior; 12 items; e.g., ‘I always buy it if I really like it’ ; Cronbach’s alpha = .83) and a situational component (i.e., the available time and money that is needed to buy on impulse; 4 items; e.g., ‘I cannot afford unplanned purchases’ ; Cronbach’s alpha = .09). A total score based on the sum of the cognitive and affective component can be calculated to evaluate the impulsive buying tendency of an individual ( Cronbach’s alpha = .89). Higher scores represent a stronger tendency to buy on impulse. Financial decision styles questionnaire. The Financial Decision Styles questionnaire (FDS) is used to evaluate five decision styles an individual can use when making financial decisions (Bangma et al., 2017, 2019). The FDS consists of 24 statements which differentiate a rational decision style (i.e., evaluating options before making a decision; 5 items; Cronbach’s alpha = .69), an intuitive decision style (i.e., relying on feelings and emotions when making a decision; 5 items; Cronbach’s alpha = .79), a dependent decision style (i.e., requiring the advice of others when making a decision; 5 items; Cronbach’s alpha = .82), an avoidant decision style (i.e., avoiding or postponing making a decision; 5 items; Cronbach’s alpha = .89), and a spontaneous decision style (i.e., being impulsive when making a decision; 4 items; Cronbach’s alpha = .74). For each statement, participants have to indicate to what extent a situation applies