Dynamics of Affective Habituation to Touch Differ on the Group and Individual Level.

Slow stroking touch activates C-tactile (CT) fibres in the human skin and is typically described as pleasant. Over a longer duration of stroking, affective habituation sets in, indicated by a reduction in rated pleasantness. However, it is not clear whether the group level effect is represented on an individual level. We analyse the stability of individual ratings of slow stroking touch and their relationship to behavioural and physiological measures. Forty-eight participants (23 women) were repeatedly stroked with a velocity maximally activating CT fibres. The perceived pleasantness was rated on a visual analogue scale. In order to examine the stability of pleasantness ratings, the experiment was repeated after a couple of days. During the experiment, electrocardiogram (ECG) and facial-electromyography (EMG) data were recorded. On the group-level, previous results of affective habituation to touch were replicated and stable across sessions. On the individual level, however, less than half of the participants showed a significant reduction of pleasantness in the course of the experiment. Moreover, the remaining participants showed either no change, random rating behaviour or even an increase in pleasantness ratings during the course of the experiment. The individual response patterns were variable across sessions but stable above the chance level. Furthermore, the response patterns could not be explicitly associated with any of the behavioural or physiological measures. Our findings indicate a lack of group-to-individual generalizability for affective habituation to touch. The variability of rating patterns over time indicates that they are not conclusively determined by stable individual characteristics. Future research investigating touch should favour a more individual approach to the more commonly applied group analysis.

Null Effect of Olfactory Training With Patients Suffering From Depressive Disorders-An Exploratory Randomized Controlled Clinical Trial.

Due to a close functional relation between brain areas processing emotion and those processing olfaction, major depression is often accompanied by reduced olfactory function. Such hyposmia can be improved by regular olfactory training (OT) over several months. As this training furthermore improves subjective well-being, we explored whether OT is a useful complementary strategy for depression treatment. A total of 102 depressive outpatients were randomly assigned to OT or a control training condition, which were performed twice a day for 16 weeks. Compliance was continuously monitored. Before and after training we measured depression severity and olfactory function. About half of the patients of both groups did not complete the training. Among the remaining patients, depression severity decreased significantly in both groups. The absence of an interaction effect indicated no selective impact of OT and the variance of depression improvement explained by OT was as little as 0.1%. The low compliance suggests that OT is not feasible for large parts of our sample of depressive outpatients, most likely due to a disease-immanent lack of motivation. In those patients who completed the training, lack of specific effects suggest that OT is not more useful then unspecific activation or attention training. CLINICAL TRIAL REGISTRATION: This clinical trial was registered at German Registry for Clinical Trials (DRKS), main ID: DRKS00016350, URL: http://www.drks.de/DRKS00016350.

Right between the eyes: Corrugator muscle activity tracks the changing pleasantness of repeated slow stroking touch.

Subjective reports and physiological responses provide different appraisals of sensory input. The coherence between subjective and physiological responses to repeated pleasant stimuli remains largely unexplored, and is particularly important in situations where subjective responses are prone to cognitive or contextual bias. Here, we investigate how subjective and physiological responses to repeated gentle touch correspond at two separate sessions and compare these to responses obtained when smelling an odorant. Forty-eight participants underwent 60 trials of skin-to-skin slow stroking touch directed to the forearm. We collected subjective pleasantness reports, recorded facial electromyography (EMG) of the corrugator and zygomaticus muscles and heart-rate variability (HRV). With increasing touch repetitions, mean ratings of pleasantness decreased and corrugator muscle activity increased during session 1, whereas zygomaticus activity remained largely unchanged during both sessions. HRV was significantly higher during the first session, but did not increase from baseline during either sessions. Touch was rated as more pleasant than odor, and demonstrated greater resilience to satiety than the odor responses. Facial EMG recordings of the corrugator muscle appear to be a relevant measure for capturing satiety effects in skin-to-skin touch. Zygomaticus and HRV responses were independent of the subjective appraisal of the gentle touch. Rather than being blueprints of the subjective reports, physiological responses appear to reflect different parts of the subjective experience. As such, an improved understanding of the subjective and physiological responses to pleasant stimuli may improve our understanding of the dynamic interactions that take place in shaping complex emotional phenomena, such as aversion and pleasantness.

Trait Emotional Intelligence and Relationship Satisfaction: The Mediating Role of Dyadic Coping.

Trait emotional intelligence (TEI) is an important individual difference variable that is related to the quality of romantic relationships. The present study investigated the associations between TEI, dyadic coping, and relationship satisfaction. A convenience sample of N = 136 heterosexual couples was recruited online. When the actor-partner interdependence model was applied to the data, TEI showed a positive actor effect and a positive partner effect on relationship satisfaction. The actor effect and partner effect of TEI on relationship satisfaction were partially mediated through positive dyadic coping and common dyadic coping, respectively. A small total indirect actor effect was also found for negative dyadic coping. Controlling for potential content overlap between TEI and relationship satisfaction did not alter the results. However, removing variance from the TEI score that was shared with the Big Five trait factors attenuated TEI's actor and partner effects on relationship satisfaction and rendered all but one actor effect for TEI on dyadic coping and all but one indirect effect nonsignificant. The results underline the importance of TEI for the quality of romantic relationships and they shed light on underlying mechanisms. Implications for theory, research, and applications in counseling contexts will be discussed.

The impact of severity, course and duration of depression on olfactory function.

BACKGROUND: People with diagnosed depression often express a reduced olfactory capacity, although previous studies exhibited mixed results. However, research focused mainly on psychiatric inpatients and potential influence variables were rarely considered. We therefore examined the influence of severity, course and duration of depression on olfactory function. METHODS: 101 out-patients with depressive disorders (mean age = 37.8y, SD = 12.6y; 64 women) underwent a detailed medical anamnesis, tests of olfactory threshold and identification and tests of cognitive function. The participants were grouped according to their severity, course and duration of depression. RESULTS: While severity of depressive symptoms did not affect olfactory function, course and duration of depression did. Recurrent depressive disorders were associated with reduced odor identification, and the duration of disease was negatively related to odor threshold. Those results were partly explained by reported frequent colds, which were more prevalent among long lasting depressive patients, and by poor verbal fluency, which was more frequent among recurrent depression. LIMITATIONS: The interpretation is limited by the cross-sectional research design that does not allow causal interpretation, and by the assessment of medical history which was based on patients´ reports. CONCLUSIONS: Our results support the idea that depression is not uniformly related to olfactory impairment, but depends on duration and course of depression. The results generate the hypothesis that reduced olfactory identification is caused by cognitive impairment in recurrent depression. Moreover, the relation between olfactory threshold and depression might be partially caused by a cumulative damage of the olfactory epithelium after frequent respiratory diseases.