Fig 1.
The procedure was divided into three main steps: acclimation and questionnaires, two experimental blocks, and the evaluation phase. Initially, participants acclimated to the environment and completed questionnaires. Following this, they underwent two blocks of pictures viewing sessions, each consisting of three sets of images (pleasant, neutral, and unpleasant), each set consisting of a consecutive presentation of 20 pictures lasting for 2 minutes and followed by a 2-minute resting period. Block 1 presented images with social content, while Block 2 presented non-social images. The order of block presentations and emotional conditions was counterbalanced across the participants. Finally, participants evaluated the valence and arousal of all pictures using two 9-point scales.
Fig 2.
Example of a thermal response.
Typical thermal variations as a function of time (red line) for one NA participant in response to the unpleasant set of the social block. The blue shaded part represents the 2-minute stimulation period. The hatched area represents the integral of temperature variations.
Table 1.
Empathy and clinical scores of the three groups: without alexithymia (NA), and with affective (AA) and cognitive alexithymia (CA). IRI = Interpersonal Reactivity Index, IRI sub-scales: IRI-FS = Fantasy, IRI-PD = Personal Distress, IRI-PT = Perspective Taking, and IRI-EC = Empathic Concern; SP = Social Phobia; STAI = State-Trait Anxiety Inventory; BDI-II = Beck Depression Inventory-II, SD = standard deviation. Values in the same row not sharing the same index differ significantly at p < .05 in the bilateral equality test for column means. The tests are adjusted for all pairwise comparisons within a row using Bonferroni correction.
Fig 3.
Interaction Effects of Social and Emotional Context on LF-HRV and HF-HRV in non-alexithymia (NA), cognitive (CA) and affective (AA) alexithymia.
The arousal effect (Emotion – Neutral) on the A) high frequencies (HF-HRV) and B) low frequencies (LF-HRV) heart rate variability in NA (green), CA (blue) and AA (orange) for non-social (top panels) and social sets (bottom panels). Positive values indicate greater HF-HRV or LF-HRV for emotional compared to neutral sets. Error bars represent the standard error of the mean.
Fig 4.
Effect of the social content on thermal variations in non-alexithymia, cognitive and affective alexithymia.
A) Thermal variations as a function of time in NA (green), CA (blue), and AA (orange) for non-social (top panel) and social sets (bottom panel). B) The social content effect (NS – SO) on the integral of the thermal variations in NA (green), CA (blue), and AA (orange). For panel B), Positive values indicate greater thermal variations for non-social compared to social sets. In this context, negative values indicate a greater decrease in nose temperature in response to non-social stimulation compared to social stimulation. Error bars represent the standard error of the mean.
Fig 5.
Psychophysiological Correlates Across Social and Emotional Contexts.
Correlations between psychological measures and physiological responses. (A) Nose temperature variation in social context versus state anxiety (STAI-A). (B) Nose temperature variation in a non-social context versus depression (BDI-II). (C) Social content effect (NS – SO) on nose temperature variation versus personal distress (IRI-PD) for affective alexithymia (AA) participants. Positive values indicate greater thermal variations for non-social (NS) compared to social (SO) sets. Negative values indicate a greater decrease in nose temperature for the social compared to the non-social sets. (D) High-frequency heart rate variability (HF-HRV) during social emotional context versus social anxiety (Liebowitz’s Social Phobia Scale). Red lines represent linear regression fits, with gray areas indicating 95% confidence intervals. Each dot represents an individual participant’s data point. AA = participants with affective alexithymia (orange), CA = participants with cognitive alexithymia (blue), NA = participants without alexithymia (green).