A new study led by Flinders University finds both autistic and non-autistic suspects may be judged more harshly if any idiosyncratic behaviours in interviews stray beyond what observers consider as normal.
The research also undermines the widely held perspective - referred to as the 'double empathy hypothesis' - that autistic people can better 'read' differing intentions and motivations in other autistic people, more than non-autistic people can.
In making fair courtroom judgements or conducting police interviews, the researchers warn that law enforcement agencies must guard against assumptions of guilt based on communication styles and interpretations of suspect responses, intentions and motivations.
The research, published in American Psychological Association (APA) journal Law and Human Behavior, explores two main issues.
"First, there is the view that autistic people will be judged more harshly, purely because of any 'unusual' behavioural characteristics commonly associated with autism," says experimental psychologist Emeritus Professor Neil Brewer, who has a lengthy research career focusing on eyewitness accounts and adults with autism.
"Second, we also assessed the widely held view that both autistic and non-autistic people might only have trouble 'reading' the intent of suspects who do not share the same diagnostic status and, hence, potentially judge their intentions and motivations more harshly.
"However, we found no decisive evidence in line with either of these expectations."
The two experiments tested the oft-held views that autistic people are more likely to be evaluated unjustly by others because of society's 'normative expectations' in communicating, as well as the 'double empathy' hypothesis aligning the ability of autistic and non-autistic observers to accurately 'read' an autistic suspect's responses.
Large samples of autistic and non-autistic observers were asked to evaluate autistic and non-autistic 'suspects' who took part in mock police interviews about accusations of computer hacking. The observers rated the suspects on dimensions of suspiciousness, credibility, guilt and expectancy violations (when a suspect doesn't communicate in a way an observer would expect).
Suspect participants were chosen because, when involved in a mock police interview, they displayed either high or low levels of speech hesitation or difficulties interpreting figurative language - two behaviours that strongly differentiated samples of autistic and non-autistic interviewees.
Professor Brewer, from the College of Human Sciences and Culture, and colleagues including fellow Flinders University autism expert Professor Robyn Young, say the findings suggest that some autistic suspects may face particular credibility risks in investigative or legal contexts - but the same probably applies to some non-autistic suspects.
"The important thing is the extent to which someone's behaviour violates expectations about how a suspect 'should' behave," says Professor Young, who leads the Flinders Autism Research Initiative at the College of Human Sciences and Culture at Flinders University.
Another Flinders University co-author of the article, clinical psychologist Dr Alliyza Lim, says the study provides important information for both policing and courtroom contexts, because communication behaviour may affect perceived credibility without necessarily providing evidence about whether the person actually committed an offence.
The new article - 'How behavioral differences between autistic and non-autistic suspects in forensic interviews affect observers' evaluations: Evidence for expectancy violations theory but not the double empathy hypothesis' (2026) by Neil Brewer, Carmen A Lucas (Flinders University), Katie Logos (Adelaide University), Robyn L Young and Alliyza Lim - has been published in APA Law and Human Behaviour. DOI: 10.1037/lhb0000679.
Acknowledgements: This research was supported by Australian Research Council Discovery Program funding to Prof N Brewer and Prof RL Young (Grant DP 190100162). See related articles here and here.
