Autism Spectrum Condition (ASC) is defined as a neurodevelopmental condition marked by challenges in social communication, social interaction, and a tendency towards repetitive behaviours. Autistic individuals often exhibit deficits in social cognition and perception, executive functioning, and atypical perceptual and information processing compared to non-autistic peers. This thesis explores action perception, imitation, and motor imagery in autistic individuals, aiming to gain a comprehensive understanding of how these cognitive motor processes presented in this population. Chapter 2 begins with a systematic review of autistic individuals' perception of Biological Motion (BM) and actions. This review highlights that while autistic individuals display proficiency in speed discrimination, they encounter significant challenges with tasks that require cultural or social knowledge. These include interpreting how an action is performed or understanding the intentions behind actions. Autistic children, in particular, demonstrate greater difficulties in comprehending and interpreting BM across a variety of tasks when compared to autistic adolescents and adults. Furthermore, the review did not find evidence that stimulus type, motion variety, and instructional methods markedly influence performance within the autistic population. Additionally, challenges in processing or interpreting non-biological motion were found to impact the ability to accurately perceive and respond to BM. Chapter 3 builds on the systematic review by comparing the same participants performing both a socially relevant and less socially relevant task of vitality form and speed discrimination respectively. Additionally, this study also examines the impact of different gesture types on action perception, comparing transitive gestures (e.g., moving a cup) with intransitive gestures (e.g., showing a hand gesture). For the vitality form discrimination task, participants are asked to rate the action on a scale from gentle to rude. In the speed task, they assess how quickly the action is performed, ranging from fast to slow. Autistic adults performed similarly to non-autistic adults in discriminating action speed and vitality form, with better performance in speed tasks. However, they showed shorter gaze durations on hand gestures compared to cup conditions. Chapter 4 used an imitation task that incorporates simple pointing and complex rotating gestures to further investigate the impact of attentional instructions, which have been previously demonstrated to improve imitation performance in autism. As with prior studies, participants replicated a previously observed movement sequence that varied by vertical amplitude, either direct or elevated. A concurrent imitation condition was also included in which participants performed the action while viewing the action for a second time. The level of imitation was assessed through modulation; the difference in vertical amplitude between the direct and elevated conditions. Although autistic adults displayed similar levels of modulation, they made more errors in complex gestures compared to the non-autistic group. Notably, under general instructions, both groups modulated their movements more similarly to the demonstrator. Furthermore, movement modulation was greater with attentional instructions and concurrent imitation condition, although this compromised accuracy. Chapter 5 utilizes an online Fitts' paradigm to examine Motor Imagery (MI), specifically the ability to mentally rehearse actions without physically executing them, in autistic adults. Performance in executing, perceiving, and imagining hand movements was compared with non-autistic adults. Participants engaged in tasks that required actual moving, imagining moving, and watching a presented video moving then judging if they could move their index finger between two targets on screen, with varying levels of difficulty. Both groups demonstrated a relationship consistent with Fittsâ Law across all tasks, exhibiting a positive correlation between movement times and task difficulty. This indicates that autistic adults are capable of using MI. However, differences emerged in the perception and imagination tasks indicating that autistic individuals may adopt alternative strategies when completing those tasks. In summary, this thesis provides valuable insights into the competencies of autistic adults in action discrimination, imitation, and MI, showing that they can perform comparably to non-autistic individuals across these areas. However, some patterns of difference suggest that autistic adults may employ alternative strategies to complete these tasks. The research highlights the potential benefits of detailed and attention-focused instructions in enhancing performance in complex or challenging scenarios. Additionally, these findings suggest that autistic adults possess or have developed effective strategies for managing certain social interactions and, with targeted instructions, may further improve performance in more demanding and complex contexts.
| Date of Award | 18 Jul 2024 |
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| Original language | English |
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| Awarding Institution | - The University of Manchester
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| Supervisor | Emma Gowen (Main Supervisor) & Ellen Poliakoff (Co Supervisor) |
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