Autism-spectrum quotient
The Autism-Spectrum Quotient (AQ) is a 50-item self-report questionnaire developed to assess the degree to which adults of normal or above-average intelligence exhibit autistic traits across five domains: social skills, attention switching, attention to detail, communication, and imagination.[1] Introduced in 2001 by Simon Baron-Cohen and colleagues at the Cambridge Autism Research Centre, the AQ serves as a screening tool to quantify subthreshold autistic characteristics in the general population, distinguishing it from diagnostic instruments by focusing on trait dimensionality rather than clinical thresholds.[2] Each of the 50 items presents statements rated on a four-point Likert scale ("definitely agree," "slightly agree," "slightly disagree," "definitely disagree"), with responses scored to reflect autistic-like tendencies (1 point for endorsements aligning with autism traits, 0 otherwise).[1] Total scores range from 0 to 50, with higher scores indicating greater autistic traits; subscale scores (0–10 per domain) provide additional granularity, though the overall score is most commonly used.[3] Normative data from meta-analyses show mean scores of approximately 16.4 in non-autistic adults (with males averaging higher than females at 17.0 vs. 15.9), while individuals with autism spectrum disorder (ASD) average around 35.8; suggested cutoffs for "consistent with autism" are ≥26 for males and ≥27 for females, though these vary by study and require clinical context for interpretation.[4][2] The AQ demonstrates solid psychometric properties, including test-retest reliability of r = 0.70 and internal consistency (Cronbach's α) ranging from 0.63 to 0.77 across subscales, supporting its construct validity in differentiating ASD groups from controls (e.g., 80% of high-functioning autism/Asperger syndrome participants scored ≥32 vs. 2% of controls).[2] It has been widely adopted in research and clinical settings for adults aged 16 and older, often as part of multi-method ASD assessments, and translated into 43 languages, though limitations include potential gender biases (lower sensitivity in females) and influences from co-occurring conditions like anxiety.[3][4][5] Shorter versions, such as the 28-item AQ-Short or 10-item AQ-10, have been validated for broader screening but retain the original's core focus on trait measurement.[6]History and Development
Origins and Creators
The Autism-Spectrum Quotient (AQ) was developed by Simon Baron-Cohen, Sally Wheelwright, Richard Skinner, Joanne Martin, and Emma Clubley at the Autism Research Centre, University of Cambridge, in the United Kingdom.[1] This collaborative effort emerged from the centre's focus on autism spectrum conditions, aiming to create tools for quantifying traits associated with autism in individuals with normal intelligence.[7] The primary motivation for the AQ stemmed from the need to identify subclinical autistic traits—often referred to as the "broader autism phenotype"—in the general population and among high-functioning individuals, including those without a formal diagnosis.[1] Prior to its development, no brief, self-administered instruments existed to measure the degree of autistic traits in adults of average or above-average intelligence, limiting research into the continuum between clinical autism and typical development.[7] The tool was designed to facilitate comparisons across groups, such as scientists and mathematicians, and to serve as an initial screening aid for potential diagnostic referrals.[1] Developed during the 1990s at the Autism Research Centre, the AQ underwent piloting over several years, with early versions relying on interview formats before evolving into a self-administered questionnaire, finalized in February 1998.[1] Its creation was influenced by theories of the autism spectrum as a continuum (Wing, 1988) and evidence for the broader autism phenotype (Bailey et al., 1995). The development was supported by funding from the UK Medical Research Council, the McDonnell-Pew Centre for Cognitive Neuroscience, and the Three Guineas Trust.[1]Initial Publication and Validation Studies
The Autism-Spectrum Quotient (AQ) was first published in 2001 by Simon Baron-Cohen and colleagues in the Journal of Autism and Developmental Disorders.[1] The paper introduced the AQ as a 50-item self-report questionnaire designed to quantify autistic traits in adults with normal intelligence, emphasizing its utility in placing individuals on a continuum from autism to normality.[1] The initial validation study involved multiple groups to assess the instrument's ability to discriminate between those with autism spectrum conditions and neurotypical individuals. In the primary validation sample, 58 adults diagnosed with Asperger syndrome (AS) or high-functioning autism (HFA)—45 males and 13 females—achieved a mean AQ score of 35.8 (SD = 6.5).[1] This was compared to 174 randomly selected controls (76 males, 98 females) with a mean score of 16.4 (SD = 6.3), as well as 840 Cambridge University students (mean 17.6, SD = 6.4) and 16 winners of the UK Mathematics Olympiad (mean 24.5, SD = 5.7).[1] Statistical analysis revealed significant differences, with the AS/HFA group scoring markedly higher than controls (F(1, 228) = 328.9, p < .0001).[1] Additional targeted groups, such as the mathematicians, showed elevated scores relative to general controls but lower than the clinical group, supporting the AQ's sensitivity to subclinical autistic traits.[1] Key discriminatory findings centered on a cutoff score of 32 or higher, where 80% of the AS/HFA group scored above this threshold compared to only 2% of controls.[1] This threshold yielded a sensitivity of 79.3% for identifying AS/HFA and a specificity of 98% for ruling out the condition in controls.[1] The study also noted sex differences, with males in the control groups scoring higher on average than females, though the AS/HFA group exhibited no such disparity.[1] While the paper briefly mentioned potential adaptations for other populations, it focused primarily on establishing the AQ's foundational psychometric properties in this adult sample.[1]Format and Administration
Questionnaire Items and Domains
The Autism-Spectrum Quotient (AQ) is a 50-item self-report questionnaire designed to assess the degree to which adults exhibit traits associated with the autism spectrum.[1] Each item presents a statement about everyday behaviors or preferences, and respondents rate their agreement on a 4-point Likert scale: definitely agree, slightly agree, slightly disagree, or definitely disagree.[1] The items are grouped into five conceptual domains, with 10 items per domain, to capture key aspects of autistic traits: social skill, attention switching, attention to detail, communication, and imagination.[1] The social skill domain evaluates difficulties in social interactions, such as preferring solitary activities. The attention switching domain assesses challenges in shifting focus or adapting to changes, often reflected in a preference for routines. Attention to detail items probe a tendency toward noticing small particulars over the big picture. The communication domain examines nuances in verbal and nonverbal exchanges, including literal interpretations or perceived impoliteness. Finally, the imagination domain explores difficulties in engaging with fictional scenarios or empathizing through pretend play.[8] Representative examples include: "I prefer to do things with others rather than on my own" from the social skill domain (reverse-scored, such that disagreement indicates stronger autistic traits); "I prefer to do things the same way over and over again" from attention switching; and "I often notice small sounds when others do not" from attention to detail.[1] These items are crafted to identify subtle autistic characteristics on a continuum, without assuming a clinical diagnosis.[1] The AQ is self-administered, requiring no professional oversight during completion, and typically takes 10-15 minutes.[9] It is intended for adults (aged 16 years and older) without intellectual disability (IQ > 70).[8][9]Scoring Procedure
The Autism-Spectrum Quotient (AQ) consists of 50 self-report items, each scored dichotomously as 0 or 1 point based on the respondent's agreement or disagreement with statements reflecting autistic traits.[1] For positively phrased items that endorse autistic-like behaviors (e.g., those assessing difficulties in social interaction or attention switching), a response of "definitely agree" or "slightly agree" receives 1 point, while "slightly disagree" or "definitely disagree" scores 0.[1] Conversely, for negatively phrased items that describe neurotypical traits (e.g., "I find social situations easy"), a response of "definitely disagree" or "slightly disagree" scores 1 point, indicating an autistic-like response, with agreement scoring 0.[1] As an example, on a social skills item phrased positively for neurotypical ease in interactions, selecting "slightly disagree" would score 1 point.[1] The total AQ score is calculated by summing the points from all 50 items, yielding a possible range of 0 to 50, where higher scores indicate greater endorsement of autistic traits.[1] In standard administration, only the total score is used for interpretation, although the items are grouped into five domains (social skills, attention switching, attention to detail, communication, and imagination) that can be analyzed separately for research purposes, each with subscores ranging from 0 to 10.[1]Interpretation of Scores
Score Ranges and Norms
The Autism Spectrum Quotient (AQ) yields total scores ranging from 0 to 50, based on 50 items scored dichotomously (0 or 1) from 4-point Likert responses, where endorsements reflecting autistic traits are scored as 1. In the general population of neurotypical adults, scores are typically normally distributed, with a mean around 16 to 17 and a standard deviation of approximately 6.[10] A systematic review of 69 studies encompassing over 6,900 non-clinical adults confirmed an overall mean AQ score of 16.94 (95% CI: 16.4–17.4), with a pooled standard deviation of 5.59, indicating that the majority of neurotypical individuals score below 26.[10] Population norms vary by demographic factors. Initial validation in a UK sample of 174 controls reported a mean of 16.4 (SD = 6.3). Larger analyses reveal consistent gender differences, with males scoring higher than females; for instance, means of 17.89 for males and 14.88 for females (95% CI: 13.3–16.5) across aggregated studies.[10] Scores are also elevated in science, technology, engineering, and mathematics (STEM) professions compared to non-STEM fields, as evidenced by a UK study of over 450,000 adults where STEM workers averaged 21.92 (SD = 8.92) versus 18.92 (SD = 8.48) for non-STEM.[11]| Group | Mean AQ Score | Standard Deviation | Sample Size | Source |
|---|---|---|---|---|
| Neurotypical Adults (Overall) | 16.94 | 5.59 | 6,900+ | Ruzich et al. (2015)[10] |
| Males | 17.89 | Not specified | Aggregated | Ruzich et al. (2015)[10] |
| Females | 14.88 | Not specified | Aggregated | Ruzich et al. (2015)[10] |
| STEM Professions | 21.92 | 8.92 | 450,394 | Baron-Cohen et al. (2015)[11] |
| Non-STEM Professions | 18.92 | 8.48 | 450,394 | Baron-Cohen et al. (2015)[11] |