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Additional file 1: Table S1. Reaction time (in ms) as a function of target and crowd emotional expression in unmedicated and medicated depressed participants. Table S2. Latency to target (in ms) as a function of target and crowd emotional expression in unmedicated and medicated depressed participants. Table S3. Number of distinct distractor faces fixated before target fixation as a function of target and crowd emotional expression in unmedicated and medicated depressed participants. Table S4. Mean fixation time (in ms) per distractor face before target fixation as a function of target and crowd emotional expression in unmedicated and medicated depressed participants. Table S5. Mean fixation time (in ms) on target as a function of target and crowd emotional expression in unmedicated and medicated depressed participants.

Background: The concept of alexithymia is characterized by difficulties identifying and describing one's emotions. Alexithymic individuals are impaired in the recognition of others' emotional facial expressions. Alexithymia is quite common in patients suffering from major depressive disorder. The face-in-the-crowd task is a visual search paradigm that assesses processing of multiple facial emotions. In the present eye-tracking study, the relationship between alexithymia and visual processing of facial emotions was examined in clinical depression. Materials and Methods: Gaze behavior and manual response times of 20 alexithymic and 19 non-alexithymic depressed patients were compared in a face-in-the-crowd task. Alexithymia was empirically measured via the 20-item Toronto Alexithymia-Scale. Angry, happy, and neutral facial expressions of different individuals were shown as target and distractor stimuli. Our analyses of gaze behavior focused on latency to the target face, number of distractor faces fixated before fixating the target, number of target fixations, and number of distractor faces fixated after fixating the target. Results: Alexithymic patients exhibited in general slower decision latencies compared to non-alexithymic patients in the face-in-the-crowd task. Patient groups did not differ in latency to target, number of target fixations, and number of distractors fixated prior to target fixation. However, after having looked at the target, alexithymic patients fixated more distractors than non-alexithymic patients, regardless of expression condition. Discussion: According to our results, alexithymia goes along with impairments in visual processing of multiple facial emotions in clinical depression. Alexithymia appears to be associated with delayed manual reaction times and prolonged scanning after the first target fixation in depression, but it might have no impact on the early search phase. The observed deficits could indicate difficulties in target identification and/or decision-making when processing multiple emotional facial expressions. Impairments of alexithymic depressed patients in processing emotions in crowds of faces seem not limited to a specific affective valence. In group situations, alexithymic depressed patients might be slowed in processing interindividual differences in emotional expressions compared with non-alexithymic depressed patients. This could represent a disadvantage in understanding non-verbal communication in groups.

Background Clinical depression is characterized by high levels of negative affect (NA) and attenuated positive affect (PA). Psychological and pharmacological treatments have been shown to reduce NA and to enhance PA in depressed patients. Following dual-process models, two types of affect can be distinguished: explicit (or self-reported) affect, which is formed by conscious reflections, and implicit affect, which relates to automatic affective reactions. The present study was conducted to examine, for the first time, both implicit and explicit affectivity in patients suffering from acute depression. Moreover, changes in patients’ implicit and explicit affectivity were investigated over the course of inpatient treatment. Methods Thirty-nine patients suffering from major depression and 39 healthy individuals participated in the study. Implicit affectivity was assessed using the Implicit Positive and Negative Affect Test. The explicit state and trait affectivity were measured by the Positive and Negative Affect Schedule. The level of depressive symptoms was assessed with the Beck Depression Inventory. Tests were administered to patients after admission and after 7 weeks of therapy, whereas healthy controls were investigated only once. We examined whether either comorbidity or antidepressant medication has an effect on affectivity. Results Patients with acute depression had lower implicit and explicit PA scores and higher implicit and explicit NA scores than the healthy controls. After treatment, patients’ level of depression decreased significantly. At posttreatment, patients exhibited heightened implicit and explicit PA and diminished explicit trait NA. Independent of antidepressant medication and comorbidity, no significant change in implicit NA was observed over the course of treatment. Implicit NA was correlated with explicit NA in acute depression but not during recovery. Conclusions Acute depression appears to be characterized by decreased implicit and explicit PA and increased implicit and explicit NA. After 7 weeks of treatment, depressed patients’ implicit and explicit PA increased, and explicit trait NA decreased. No decrease in implicit NA and explicit state NA occurred over the course of treatment. Finally, it seems that in the state of acute depression, the interplay between the automatic and reflective systems could be increased for negative affectivity.