Comparison of Visual Fixation Trajectories in Toddlers with Autism Spectrum Disorder and Typical Development: A Markov Chain Model.

Francesco Masedu,Roberto Vagnetti,Marco Valenti,Monica Mazza,Maria Chiara Pino

doi:10.3390/brainsci12010010

Francesco Masedu, Roberto Vagnetti + Show 3 more

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https://doi.org/10.3390/brainsci12010010

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Abstract

Autism spectrum disorder (ASD) is a neurodevelopmental condition in which visual attention and visual search strategies are altered. Eye-tracking paradigms have been used to detect these changes. In our study, 18 toddlers with ASD and 18 toddlers with typical development (TD; age range 12–36 months) underwent an eye-tracking paradigm where a face was shown together with a series of objects. Eye gaze was coded according to three areas of interest (AOIs) indicating where the toddlers’ gaze was directed: ‘Face’, ‘Object’, and ‘No-stimulus fixation’. The fixation sequence for the ASD and TD groups was modelled with a Markov chain model, obtaining transition probabilities between AOIs. Our results indicate that the transition between AOIs could differentiate between toddlers with ASD or TD, highlighting different visual exploration patterns between the groups. The sequence of exploration is strictly conditioned based on previous fixations, among which ‘No-stimulus fixation’ has a critical role in differentiating the two groups. Furthermore, our analyses underline difficulties of individuals with ASD to engage in stimulus exploration. These results could improve clinical and interventional practice by considering this dimension among the evaluation process.

Highlights

Researchers have reported the extraordinary ability of infants to detect social stimuli [1,2]
The Markov chains associated with the autism spectrum disorder (ASD) and typical development (TD) groups are significantly different (χ2 (8) = 28.1, p < 0.001) confirming the hypothesis of different visual search behaviors
Considering the lower and upper endpoints, we found that the TD group has a greater probability to be interested in faces (25%) or objects (55%) compared with the ASD group (14% and 37%, respectively)

Summary

Introduction

Researchers have reported the extraordinary ability of infants to detect social stimuli [1,2]. Some authors [3,4,5] have shown that infants can efficiently detect faces within complex visual scenes. Researchers have generally used the visual search paradigm to evaluate the capacity to detect and perceive a stimulus. This paradigm is based on the idea that if attention is drawn automatically to the target stimulus the search time will be unaffected, or minimally affected, by the number of distractors that are present [8]. In the worldwide general population, the autism spectrum disorder (ASD) prevalence is estimated to be around 1%, based on screening and register-based studies [17]

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