## 4 Discussion  
This study was specifically aimed at evaluating the behavior of ASD children, in comparison with typically developing children (TD), during standardized EAA sessions. Overall, data indicate that interaction with a horse is able to elicit social interactions and communicative behaviors in a sex- and age-dependent fashion in ASD children. Furthermore, we were able to show that previous experience with EAAs can improve interpersonal distance and some interactions with the horse (i.e., grooming), suggesting that positive effects resulting from EAAs may build over time. ASDs are characterized by impairment in social communication and social interaction, as well as repetitive and unusual sensory-motor behaviors [10]. As expected, in our study, we found that ASD children showed more withdrawal/avoidance from the horse and more  
Figure 2: (**a**) Duration (time spent/total time observed in minutes) of closeness, (**b**) grooming (duration), (**c**) physical contact (duration), (**d**) frequency (number of events/total time observed in minutes) of visual contact in ASD children (black bars) and in TD children (white bars) with EAA experience of \(\leq\)1 month or \(>\)1 month; \({}^{*}\)\(p\) < 0.01; \({}^{**}\)\(p\) < 0.001.  
problem behaviors. Likewise, they displayed significantly less visual and physical contact with the horses than children with TD, indicating social and communicative deficits. Female ASD children showed more withdrawal/avoidance from the horse than female TD, while male ASD children displayed less visual and physical contact with the horse and more problem behaviors than their TD counterparts. ASD is characterized by a higher prevalence in males than females [41] and higher symptomatology in the female gender [42]. These data indicate a clear sex difference in the behaviors shown by the two sexes, although data have to be taken with caution as the number of female ASD children recruited in this study was less than half the number of males. When we considered the interaction effects between diagnosis and age on children's behaviors, we observed that younger ASD children (5-9 years old) showed a lower duration of physical contact with horses than younger TD children. Consistently, younger ASD children showed more problem behaviors than TD children. These differences tend to decrease with increasing age, probably as a result of an increase in social experience and overall neurobehavioural development. We grouped ASD children according to their experience with EAAs, i.e., less than 1 month of experience or above 1 month of experience. One of the most interesting results of this study is that ASD children with more EAA experience showed a higher duration of closeness to the horse and more grooming than ASD children with less experience. This is probably due to the previously learned skills concerning the approach to the horse and the use of tools for its handling (i.e., grooming). By contrast, we did not observe an effect of previous EAA experience in the case of physical and visual contact behaviors. It is of interest here that, in both ASD and TD children, the experience did not affect these behaviors, which might reflect the fact that they are not a result of experience but involve spontaneous interaction with the animal, which was found constantly lower in ASD children, compared to TD. Overall, these data can be interpreted to indicate that those behaviors that are mediated by the operator handling the sessions, such as closeness and grooming, appear more amenable to be affected by the experience compared to spontaneous interactions, which remain less pronounced in ASD children, no matter how much experience they might have with EAAs. This observation can direct future research efforts on the effect of EAAs on other domains of functioning that might be more susceptible to change than social behaviors. A promising avenue of investigation is represented by the potential use of EAAs to improve executive functioning in children with ASD.