Functional infrared thermal imaging (fITI) is considered a promising method to measure emotional autonomic responses through facial cutaneous thermal variations. However, the facial thermal response to emotions still needs to be investigated within the framework of the dimensional approach to emotions. The main aim of this study was to assess how the facial thermal variations index the emotional arousal and valence dimensions of visual stimuli. Twenty-four participants were presented with three groups of standardized emotional pictures (unpleasant, neutral and pleasant) from the International Affective Picture System. Facial temperature was recorded at the nose tip, an important region of interest for facial thermal variations, and compared to electrodermal responses, a robust index of emotional arousal. Both types of responses were also compared to subjective ratings of pictures. An emotional arousal effect was found on the amplitude and latency of thermal responses and on the amplitude and frequency of electrodermal responses. The participants showed greater thermal and dermal responses to emotional than to neutral pictures with no difference between pleasant and unpleasant ones. Thermal responses correlated and the dermal ones tended to correlate with subjective ratings. Finally, in the emotional conditions compared to the neutral one, the frequency of simultaneous thermal and dermal responses increased while both thermal or dermal isolated responses decreased. Overall, this study brings convergent arguments to consider fITI as a promising method reflecting the arousal dimension of emotional stimulation and, consequently, as a credible alternative to the classical recording of electrodermal activity. The present research provides an original way to unveil autonomic implication in emotional processes and opens new perspectives to measure them in touchless conditions.

Anxiety and depression are both characterized by dysregulated autonomic reactivity to emotion. However, most experiments until now have focused on autonomic reactivity to stimuli presented in central vision (CV) even if affective saliency is also observed in peripheral vision (PV). We compared autonomic reactivity to CV and PV emotional stimulation in 58 participants with high anxious (HA) or low anxious (LA) and high depressive (HD) or low depressive (LD) symptomatology, based on STAI‐B and BDI scores, respectively. Unpleasant (U), pleasant (P), and neutral (N) pictures from IAPS were presented at three eccentricities (0°: CV; −12 and 12°: PV). Skin conductance (SC), skin temperature, pupillary diameter, and heart rate (HR) were recorded. First, HA participants showed greater pupil dilation to emotional than to neutral stimuli in PV than in CV. Second, in contrast to HD, the valence effect indexed by SC and emotional arousal effect indexed by skin temperature were observed in LD. Third, both anxiety and depression lead to a valence effect indexed by pupillary light reflex and heart rate. These results suggest a hyperreactivity to emotion and hypervigilance to PV in anxiety. Depression is associated with an attenuation of positive effect and a global blunted autonomic reactivity to emotion. Moreover, anxiety mostly modulates the early processes of autonomic reactivity whereas depression mainly affects the later processes. The differential impact of emotional information over the visual field suggests the use of new stimulation strategies in order to attenuate anxious and depressive symptoms.

Emotional difficulties in alexithymia and their social consequences have been linked to alterations in autonomic nervous system. However, most of previous studies did not take into account the distinction between the affective and the cognitive dimensions of the alexithymia, leading to inconsistent results.Aim: In this study, we compared the effects of both dimensions of alexithymia on the autonomic arousal to emotional and social visual stimulations.Methods: Skin conductance responses (SCRs) to items of the International Affective Pictures System characterized by emotional (unpleasant, neutral, and pleasant), social (with humans) or non-social (without humans) content were recorded in non-alexithymic (NA), affective (AA) and cognitive alexithymic (CA) participants, selected on the basis of the Toronto Alexithymia Scale and the Bermond-Vorst Alexithymia Questionnaire. All participants responded to questionnaires of empathy, social phobia, depression, and anxiety before the experiment and evaluated the arousal of the pictures after it.Results: Cognitive alexithymic group showed lower amplitudes of SCRs to pictures with social than without social relevance whereas the opposite pattern was observed for the NA group. Arousal emotional effects of the pictures on SCRs did not differ among groups. In addition, CA participants showed lower scores than NA in the Personal Taking sub-scale of the empathy questionnaire, while AA showed lower scores than NA in the fantasy sub-scale. The CA group showed higher social phobia, depression and anxiety scores, than the other two groups.Conclusion: This work has two original outcomes: first, affective alexithymics expressed lower empathic affective scores than other groups; second, alexithymia modulated the impact of the social relevance of the stimuli on the autonomic reactivity, this impact vanishing in affective alexithymics and reversing in cognitive alexithymics. Thus, though the groups could not be distinguished on the basis of emotional effect on SCRs, they clearly differed when the empathic characteristics and the autonomic impact of social relevance were considered. Finally, the described autonomic signature to social relevant information could contribute to elucidate the difficulty of alexithymics to deal with emotions during social transactions.