Evaluating intersubjectivity: an overview of the use of Thermal Infrared Imaging in the assessment of emotional states

Intersubjectivity represents one of the most challenging psychological issue. In this field, the assessment of interlocutors’ psychophysiological and emotional states has become more and more relevant, also thanks to the collection of physiological and psychophysiological information. In the last decade, in the field of psychological research activities, innovative instrumental measures of psychophysiological and affective states have been developed, with relevant implication in the frontier of interpersonal relationships and communication. Nowadays, among the most relevant measurements of psychophysiological responses, autonomic nervous activity and emotional states, Thermal infrared (IR) imaging has been acknowledged as a very useful non-invasive technology for evaluating emotional states in social interactions. This tool allows to take over various physiological information and could then be used to infer about affective and emotional states. In this line, it is particularly employed in the investigation of various psychological issues, such as the early interactions between mother and infants, empathy, and other emotional relational conditions (stress, fear, trauma, guilt….), offering relevant information also about relational risk and psychopathological conditions. Thus, the international literature in applied psychophysiology based on the use of Thermal infrared (IR) imaging in social conditions highlights an increasing interest in this technique, especially for the contribution to advancing neuroscience and human–machine interaction studies. The present study intends to give a theoretical overview of the investigation of affective and emotional states through the tool of the Thermal infrared (IR) imaging, specifically focusing on the principal achievements in the issue of caregiver-infant relationship, and also stressing potentialities and limits of psychophysiological researches. The review of international literature was made through researches in university libraries on paper material, and telematics systems research. Particularly useful database were ProQuest, PsyArticles, PsyInfo, PubMed, together with the use of Scopus index to verify the papers’ scientific relevance. As proved by the great number of international empirical studies assessing the emotional and affective states of the interlocutor, the Thermal infrared imaging (IR) represents a very innovative advancement in the knowledge of neurophysiological bases of emotions and of the link between psychophysiological responses and affective conditions. The state of art of international research showed the relevance of the empirical studies which used the tool of Thermal infrared imaging in the understanding of empathy and social interactions. Indeed, many studies highlighted the capability of thermal IR imaging to catch emotional states in many everyday life scenarios. Compared to classical technology for assessing autonomic activity, Thermal infrared imaging represents a non-invasively, ecologically, and contact free tool, bringing in itself positive implications for individual compliance and participations in research. Investigating affective and psychophysiological states of individuals is crucial to address the social and relational issue in environmental conditions, also in term of potential risk and protective factors in relationships and setting any intervention plans. The attribution of psychological valence to neurophysiological measurements such as Thermal infrared imaging (IR) nurtures the debate on "thermal imprint" of emotion, and poses new and constant considerations on healthy socio-emotional interactions. Given the international relevance of the research field of intersubjectivity, such as mothers–child interactions, it should be recommended to further investigate the topic of psychophysiological assessment by an empirical way in Italian samples. This would end to better understanding the individual and relational emotional states, its clinical features and anticipate the intervention strategies. As a last resort, the physiological research on the emotional arena will shed more and more light on computational evaluation and human artificial agent interaction.