Detecting Suspicious Behaviour: The Influences of Autism and Theory of Mind

Author: Zoe Michael

  • Thesis download: available for open access on 23 Feb 2025.

Michael, Zoe, 2024 Detecting Suspicious Behaviour: The Influences of Autism and Theory of Mind, Flinders University, College of Education, Psychology and Social Work

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Despite a lack of substantial empirical support for the claim that Theory of Mind (ToM) difficulties pose a unique risk factor for criminal vulnerability in autistic defendants, it is frequently cited as a mitigating factor in defence arguments and expert testimony. It has been argued that ToM difficulties may lead people to become embroiled in criminal activity due to an inability to recognise cues to suspicious behaviour in others (Brewer & Young, 2015). Although previous research has found evidence to suggest that ToM may be related to the detection of suspicious behaviour (Brewer et al., 2018; Brewer et al., 2023), there is currently no evidence to suggest that, on a group level, autistic individuals are less likely to detect cues to suspicious behaviour within interactions (Brewer et al., 2023). This study sought to further investigate the proposition that that (1) ToM difficulties are associated with trouble detecting and responding to suspicious behaviour within interactions, and that (2) both ToM difficulties and trouble detecting suspicious behaviour are more likely to present in autistic individuals than non-autistic individuals.

To test these hypotheses, I conducted three studies. Study 1 involved the development and extensive evaluation of a novel paradigm called the Suspicious Activity Paradigm (SAP) using large samples of non-autistic adults. The SAP was created to provide a more ecologically valid measure of the detection of suspicious behaviour than tasks used in previous research (Brewer et al., 2018; Brewer et al., 2023). Study 1 demonstrated that (1) the paradigm presented a viable way of capturing an array of responses detailing how people respond to different problematic situations, (2) responses could be reliably coded within a series of categories using a comprehensive protocol, and (3) the patterns of responding across participants were relatively stable which indicated the sensitivity of the paradigm to the proposed cues to suspicion.

Study 2 then extended upon Study 1 by introducing comparison measures of ToM, autistic traits, and verbal ability for a preliminary indication of the SAP’s relationship to each measure. This study generally found no relationships between ToM or autistic traits and the SAP but highlighted significant restrictions in variability on the ToM measure. Furthermore, it indicated that verbal ability had a meaningful association with SAP performance.

The third and final study involved adding an autistic sample to investigate autistic-non-autistic group differences and further explore associations between the SAP and ToM, autistic traits, and verbal ability. It also included additional measures of gullibility, social vulnerability, and interpersonal trust as potential markers of concurrent and divergent validity. Study 3 demonstrated no group-level difference in the ability to detect and respond to suspicious behaviour. It also showed that many autistic participants performed at or near ceiling on the ToM measure, which constrained the ability to detect meaningful relationships between ToM and the SAP. Nevertheless, comparison of very high and very low ToM scores demonstrated that those with poor ToM were less likely to respond adaptively or report suspicion than those with very high ToM, irrespective of diagnosis. Study 3 did not provide independent confirmation of the SAP’s convergent validity using the proposed validity markers and highlighted a need for ongoing validation in future research.

Taken altogether, my findings suggest that ToM is an important social-cognitive feature that should be considered when discussing vulnerability to criminal involvement, regardless of diagnosis. In addition, although it should not be assumed to impact all autistic individuals equally, due to the increased likelihood of prominent ToM difficulties in autistic adults, ToM should be thoroughly investigated when autistic adults appear in court as a defendant. Further research is suggested to explore the influence of intellectual ability and other characteristics of autism, and how these interact with ToM to increase vulnerability.

Keywords: Theory of Mind, criminal vulnerability, autism

Subject: Psychology thesis

Thesis type: Doctor of Philosophy
Completed: 2024
School: College of Education, Psychology and Social Work
Supervisor: Emeritus Professor Neil Brewer