Previous research has indicated that people with autism spectrum disorders (ASD) have fewer emotive facial expressions. However, most such research has adopted subjective and abstract methods of assessing facial expressions, and as a result, the type of facial emotions expressed by people with autism remain unknown. Furthermore, most evidence has been acquired under experimental conditions; therefore, it is necessary to research conditions more similar to social situations. The present study investigated facial movements and headnodding in adults with ASD (n＝20) and adults without any disorder (n＝20) while they introduced themselves to a stranger (Talking condition) or listened to the stranger’s self-introduction (Listening condition) We adopted the Facial Action Coding System, which is an objective and comprehensive system based on anatomy, to describe visible facial movements. Results indicated that in comparison to adults without any disorder, adults with ASD had fewer facial movements related to smiling and promoting conversations in the Listening condition. Moreover, they displayed fewer facial movements related to smiling and emphasis in conversations, such as raising eyebrows in the Talking condition. Furthermore, they displayed fewer head nods in the listing condition. These findings suggest that facial expressions of people with ASD are characterized by using fewer conversational signals such as fewer smiles, facial movements, and head nods.

The integration of somatosensory and visual information related to motor control and bodily recognition in adults with autism spectrum disorder（ASD） was investigated. The participants（N＝22, 13 men and 9 women, teens to 50s） conducted visual and non-visual tasks consisting of a figure-drawing and a tactile-discrimination task, respectively, to examine the influence of visual inputs on task performance. The results suggested that ASD adults initially had movement control difficulties while drawing in the non-visual condition. Moreover, ASD adults showed individual differences in the clarity of their body image when differentiating tactile stimuli in the non-visual condition, regardless of the task difficulty.