**4. General conclusions**

The empirical investigation of implicit and spontaneous ToM reasoning in ASD is still in an early stage. Yet, the available evidence supports the ToM hypothesis by indicating specific impairments in ASD. With regard to implicit ToM processing, available eye tracking evidence consistently indicates that implicit ToM reasoning is impaired in ASD even in high-functioning adults with ASD, who pass experimental explicit ToM tasks. Individuals with ASD seem to lack a spontaneous sensitivity to other's mental states. This specific deficit might be one origin of social-cognitive deficits and difficulties in social interactions. Further research is needed to evaluate how persistent this implicit ToM deficit is and if learning through experience, or even explicit instructions, can compensate for it. To this end more within-subject studies that systematically assess implicit and explicit ToM task performance, as well as the influence of different forms of training, are desirable.

Moreover, for a better understanding of social-cognitive deficits in ASD we need to gain more knowledge about how individuals with ASD process social signals in general, not only how they process false beliefs. According to a recent account, sensitivity to ostensive signals, such as direct gaze or addressee-directed speech, is essential for learning through social interaction [90]. An impaired processing of ostensive signals in ASD could result in insufficient learning from others, another burden in the life of individuals with ASD.

Another important issue in research on implicit and explicit ToM in autism concerns task analysis: To what extent do certain tasks require automatic, on-line tracking skills (e.g., nonverbal decoding skills) versus conscious and learned reflection on mental states (e.g., the use of mental state vocabulary when describing oneself). The REM task, for instance, requires both types of processing, since one has to decode emotions but also to ascribe the correct verbal label to the emotion. Therefore, it is difficult to pinpoint the nature of autistic individuals' impairments in the task. Similarly, self-descriptions pose complex demands on different levels of processing. Impairments of individuals with ASD may arise from deficits in the fast and automatic retrieval of self-related information as well as from an inability to express their ideas about themselves with a mentalistic vocabulary they have not fully acquired, thus leading to a less detailed and mentalistic account of themselves as individuals. Future research needs to further analyze the relative contribution of implicit and explicit skills in solving a wide array of ToM tasks.

### **Acknowledgements**

Preparation of this chapter was supported by a grant from the Volkswagen Foundation and a fellowship from the Center for Advanced Studies at LMU Munich.
