Autism‐spectrum quotient

The Autism‐Spectrum Quotient (AQ, Baron‐Cohen et al., 2001) is a continuous, quantitative self‐report measure of autistic traits in adults of normal intelligence. The questionnaire consists of 50 questions, divided into 5 subscales of 10 items each: social skill, attention switching, attention to detail, communication and imagination. Items are answered on a 4‐point Likert scale: definitely agree, slightly agree, slightly disagree, definitely disagree. Completing all items takes approximately 10 min. Both the original English version of the test and its Dutch translation show satisfactory psychometric properties (Baron‐Cohen et al., 2001; Hoekstra et al., 2008). The original scoring scheme as proposed by Baron‐Cohen et al. (2001) is binary, ignoring the degree of agreement or disagreement. In line with Austin (2005) and Hoekstra et al. (2008), we included all four levels in scoring, which yields higher internal consistency and test‐retest reliabilities than binary scoring (Stevenson & Hart, 2017), and which has been shown to improve the reliable range of measurement significantly (Murray, Booth, McKenzie, & Kuenssberg, 2016). This resulted in a minimum total score of 50 (the individual reports having no autistic traits) and a maximum score of 200 (the individual reports having the full range of autistic traits). As could be expected based on score variability, reliability was better when using the full‐range scoring scheme. Cronbach's alpha was α = 0.85 for the composite score (as opposed to α = 0.78 using binary scores), α = 0.76 (α = 0.56) for social skill, α = 0.76 (α = 0.67) for attention switching, α = 0.62 (α = 0.53) for attention to detail, α = 0.67 (α = 0.59) for communication and α = 0.57 (α = 0.50) for imagination.