Behavioural and facial thermal responses were recorded in twelve 3-4-month-old infants during the Still-Face Paradigm. As in the usual procedure, infants were observed in a three-step, face-to-face interaction: a normal interaction episode (3 min); the ‘still-face’ episode in which the mother became unresponsive and assumed a neutral expression (1 min); a reunion episode in which the mother resumed the interaction (3 min). A fourth step that consisted of a toy play episode (5 min) was added for our own research interest. We coded the behavioural responses through the Infant and Caregiver Engagement Phases system, and recorded facial skin temperature via thermal infrared imaging. Comparing still-face episode to play episode, the infants' communicative engagement decreased, their engagement with the environment increased, and no differences emerged in self-regulatory and protest behaviours. We also found that facial skin temperature increased. For the behavioural results, infants recognised the interruption of the interactional reciprocity caused by the still-face presentation, without showing upset behaviours. According to autonomic results, the parasympathetic system was more active than the sympathetic, as usually happens in aroused but not distressed situations. With respect to the debate about the causal factor of the still-face effect, thermal data were consistent with behavioural data in showing this effect as related to the infants' expectations of the nature of the social interactions being violated. Moreover, as these are associated to the infants' subsequent interest in the environment, they indicate the thermal infrared imaging as a reliable technique for the detection of physiological variations not only in the emotional system, as indicated by research to date, but also in the attention system. Using this technique for the first time during the Still-Face Paradigm allowed us to record autonomic data in a more ecological manner than in previous studies.

Pointing gesture allows children to communicate their intentions before the acquisition of language. In particular, two main purposes seem to underlie the gesture: to request a desired object (imperative pointing) or to share attention on that object (declarative pointing). Since the imperative pointing has an instrumental goal and the declarative an interpersonal one, only the latter gesture is thought to signal the infant’s awareness of the communicative partner as a mental agent. The present study examined the neural responses of adult subjects with the aim to test the hypothesis that declarative rather than imperative pointing reflects mentalizing skills. Fourteen subjects were measured in a MEG environment including 4 conditions, based on the goal of the pointing–imperative or declarative–and the role of the subject–sender or receiver of pointing. Time-Frequency modulations of brain activity in each condition (Declarative Production and Comprehension, Imperative Production and Comprehension) were analyzed. Both low BETA and high BETA power were stronger during Declarative than Imperative condition, in anterior cingulated cortex and right posterior superior temporal sulcus, respectively. Furthermore, high GAMMA activity was higher in right temporo-parietal junction during the sender than receiving condition. This suggests that communicative pointing modulated brain regions previously described in neuroimaging research as linked to social cognitive skills and that declarative pointing is more capable of eliciting that activation than imperative. Our results contribute to the understanding of the roles of brain rhythm dynamics in social cognition, thus supporting neural research on that topic during developmental both in typical and atypical conditions, such as autism spectrum disorder. In particular, the identification of relevant regions in a mature brain may stimulate a future work on the developmental changes of neural activation in the same regions.