Eye Movement Study On Social Attention In Children With Autism

Social attention is the processing of social information, mainly including the perception of social individuals, visual searching, social orientation and joint attention and so on. It sheds funding influence on early attachment, self-regulation, and cognitive ability. While Autism spectrum disorders are referred to as neurodevelopmental disorders, characterized by persistent deficits in social communication and social interaction across contexts, as well as restricted or repetitive patterns of behaviors,interests, or activities(Association, 2013), the deficits in reciprocal social interaction is one of the core specific symptoms. Social attention, as the initial step of social information processing, is a more fundamental deficit in ASD. Therefore, social attention in children with autism attracts extensive attention of researchers. Previous studies on this area often through the studying of theory of mind, executive function, emotional empathy ability and so on(eg., Geurts et al., 2004; Hughes & Russell, 1993; Sergeant et al., 2002),weakening the importance of social attention. Yet recent studies on eye movement have found that ASD showed different degree of deficits in attention, gaze orienting and joint attention etc. Certainly, there is evidence to the contrary. Besides, the developing characteristic and the pathological mechanism of social attention in ASD are still unclear, especially lacking systematic studying of different aspects of social attention.Therefore, the present study intended to use eye tracking technology, combining unidirectional and interactional social attention, to systematically investigate the gaze characteristics, patterns and possible pathological mechanism of social attention inchildren with ASD.Study 1(statically unidirectional social attention) included three experiments,involving 25 typically developing children and 49 ASD children. Experiment 1presented alone face bust photos(positive emotion), to examine the fixation pattern of ASD about face, testing the hypothesis of “excess mouth and diminished eyes”. The results showed that:(1) the total fixation duration of eyes and mouth in ASD is similar to TD children;(2) the average fixation duration of eyes in ASD were significantly less than TD, and the face looking was more scattered around the peripheral area in ASD(such as skin, hair etc.), while TD were mainly focus on the core feature area(eg., eyes,mouth and nose etc.). Experiment 2 where participants viewed pictures of natural scene inserted a human face and a normal object, explored the basic visual searching capability and processing characteristics of ASD. The results showed that:(1) The basic visual searching capability of static social stimuli in ASD is not damaged, but they spent significantly long time noticing objects embedded in the background;(2) the average looking time of face and object in ASD were significantly less than TD. Experiment 3matched a human picture with competing stimulus(circumscribed interests, CI;non-circumscribed interests, non-CI), aiming at the different fixation processing of social stimuli between TD and ASD, and exploring what impact the stimulus property will have on social information processing in ASD. The results showed that:(1) when matched with CI, ASD had a similar looking performance of face with TD, but with non-CI, ASD showed a diminished total fixation duration of face;(2) when matched with non-CI, the time to first face fixation of ASD was significantly longer than TD, but the average facing looking time was shorter;(3) ASD showed a longer fixation to CI than TD, also the average looking time to CI was longer in ASD.Study 2(dynamically interactive social attention) involved 23 ASD children and 11 TD children. This study was based on the video paradigm of Senju and Csibra(2008).We set up two kinds of conditions(simply gaze shifting; voice prompting), and each condition contained four stimulus types(toys, altered toys, plants and human beings),aiming to explore the characteristics and processing patterns of social attention in the state of dynamic activities in children with ASD. We found that:(1) as a whole, the gaze shifting accuracy of ASD was preserved;(2) when voice was added, the gaze processingof all target stimuli were significantly increased, while fixation preference in ASD was increased only in CI condition;(3) when voice added, the fixation time to target human beings and plants of ASD were significantly shorter than TD.Overall, this present study found that:(1) the proportion of eyes and mouth fixation time in ASD was similar to TD, so our findings didn’t support “diminished eyes and excess mouth” hypothesis. However, the face processing pattern in ASD was indeed different from TD, showing more attention around the peripheral area, and less attention for the core feature area.(2) The basic visual searching capability of static social stimuli in ASD is not damaged, but they are not sensitive to the conflict stimulation in the natural scene, which means ASD may have difficulty in subtracting and processing useful information.(3) On the condition of matching competing stimulus, the preference and prioritization of social attention are significantly weaker than TD, especially when matching non-CI with human picture.(4) ASDs do have special preference for CI, and they are not deficient in gaze shifting accuracy. In other words, ASDs are able to correctly orient to the direction of target objects, but unable to sustain attention, even adding voice, they can’t attach the target to social relevance yet. The present paper systematically examined the characteristics and processing mode of social attention in children with ASD from unidirectional and interactive aspects, and further analyzed the influence and possible reason which social attention deficits may had on ASD individuals. This enriched research in the field of social disorders in ASD, and can provide scientific theoretical basis for clinical early diagnosis and effective guidance for practical intervention...