Mind the social feedback : effects of tDCS applied to the left DLPFC on psychophysiological responses during the anticipation and reception of social evaluations

The left dorsolateral prefrontal cortex (lDLPFC) is implicated in anticipatory (i.e. during anticipation of emotional stimuli) and online (i.e. during confrontation with emotional stimuli) emotion regulatory processes. However, research that investigates the causal role of the lDLPFC in these processes is lacking. In this study, 74 participants received active or sham transcranial direct current stimulation (tDCS) over the lDLPFC. Participants were told strangers evaluated them. These (rigged) social evaluations were presented, and in 50% of the trials, participants could anticipate the valence (positive or negative) of the upcoming social feedback. Pupil dilation (a marker of cognitive resource allocation) and skin conductance responses (a marker of arousal) were measured. The results indicate that active (compared to sham) tDCS reduced arousal during the confrontation with anticipated feedback but only marginally during the confrontation with unanticipated feedback. When participants were given the opportunity to anticipate the social feedback, tDCS reduced arousal, irrespective of whether one was anticipating or being confronted with the anticipated feedback. Moreover, tDCS reduced cognitive resource allocation during anticipation, which was associated with resource allocation increases during the subsequent confrontation. Altogether, results suggest that the lDLPFC is causally implicated in the interplay between anticipatory and online emotion regulatory processes

Acute stress impacts reaction times in older but not in young adults in a flanker task

Acute psychosocial stress effects on inhibition have been investigated in young adults, but little is known about these effects in older adults. The present study investigated effects of the Trier Social Stress Test on cognitive inhibition (i.e., ability to ignore distracting information) using a cross-over (stress vs. control) design in healthy young (N = 50; 18-30 years; M age  = 23.06) versus older adults (N = 50; 65-84 years; M age  = 71.12). Cognitive inhibition was measured by a letter flanker task and psychophysiological measures (cortisol, heart rate, subjective stress) validated the stress induction. The results showed that while stress impaired overall accuracy across age groups and sessions, stress (vs. control) made older adults' faster in session 1 and slower in session 2. Given that session 2 effects were likely confounded by practice effects, these results suggest that acute psychosocial stress improved older adults' RTs on a novel flanker task but impaired RTs on a practiced flanker task. That is, the interaction between stress and learning effects might negatively affect response execution when testing older adults on flanker tasks. If confirmed by future research, these results might have important implications especially in settings where repeated cognitive testing is performed under acute stress. </p

Prefrontal tDCS attenuates counterfactual thinking in female individuals prone to self-critical rumination

The tendency to ruminate (i.e., repetitive negative self-referential thoughts that perpetuate depressive mood) is associated with (a) an elevated propensity to maladaptively experience counterfactual thinking (CFT) and regret, and (b) hypo-activity of the left dorsolateral prefrontal cortex (DLPFC). The goal of this study was to investigate whether anodal transcranial direct current stimulation (tDCS) over the left DLPFC, in function of self-critical rumination tendencies, momentarily reduces counterfactual thinking and regret (assessed via self-report and psychophysiological indices). Eighty healthy participants with different levels of self-critical rumination received either anodal or sham tDCS while performing a decision making task in which they were repeatedly confronted with optimal, suboptimal, and non-optimal choice outcomes. The results showed that among rumination-prone individuals, anodal (versus sham) tDCS was associated with decreased CFT and attenuated psychophysiological reactivity to the differential choice outcomes. Conversely, among low rumination-prone individuals, anodal (versus sham) tDCS was associated with increased CFT and regret, but in absence of any effects on psychophysiological reactivity. Potential working mechanisms for these differential tDCS effects are discussed. Taken together, these results provide initial converging evidence for the adaptive effects of left prefrontal tDCS on CFT and regret to personal choice outcomes among individuals prone to engage in self-critical rumination

Effects of HF-rTMS over the left and right DLPFC on proactive and reactive cognitive control

Previous research supports the distinction between proactive and reactive control. Although the dorsolateral prefrontal cortex (DLPFC) has been consistently related to these processes, lateralization of proactive and reactive control is still under debate. We manipulated brain activity to investigate the role of the left and right DLPFC in proactive and reactive cognitive control. Using a single-blind, sham-controlled crossover within-subjects design, 25 young healthy females performed the 'AX' Continuous Performance Task after receiving sham vs active high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) to increase left and right DLPFC activity. Reaction times (RTs) and pupillometry were used to assess patterns of proactive and reactive cognitive control and task-related resource allocation, respectively. We observed that, compared to sham, HF-rTMS over the left DLPFC increased proactive control. After right DLPFC HF-rTMS, participants showed slower RTs on AX trials, suggesting more reactive control. However, this latter result was not supported by RTs on BX trials (i.e. the trial that specifically assess reactive control). Pupil measures showed a sustained increase in resource allocation after both active left and right HF-rTMS. Our results with RT data provide evidence on the role of the left DLPFC in proactive control and suggest that the right DLPFC is implicated in reactive control

Psychophysiological effects of evaluative language use on Twitter complaints and compliments

This article explores the role of evaluative language in the identification of emotions in–and psychophysiological responses to–Twitter complaints and compliments by the readers of these messages. Three hypotheses were tested in this research. First, in line with recent experimental work in French, we expected the presence of negative evaluative language in complaints to increase perceived dissatisfaction, impoliteness, and offensiveness by the reader. Second, assuming the negativity bias hypothesis, stronger psychophysiological responses should be found in complaints compared to compliments. Third, readers’ psychophysiological responses should be stronger for complaints and compliments including evaluative language. To test these hypotheses, we used a reading task involving cardiovascular reactivity measurements and a questionnaire. We found that perceived customer dissatisfaction, impoliteness and offensiveness were higher in complaints with vs. without evaluative language. We did not find an effect of the negativity bias on cardiovascular reactivity. Rather, compliments with evaluative language elicited larger cardiac slowing compared to complaints (with or without evaluative language) and compliments without evaluative language. As the stimuli is our study concern a railway company (which is mostly the target of criticism and complaints on Twitter), participants may have reacted more to the sort of feedback they would not expect the company to receive. Future research will be necessary to establish whether our findings still hold in the case of companies that achieve a better balance between negative and positive feedback

When choosing means losing : regret enhances repetitive negative thinking in high brooders

Past research suggests a relation between rumination (i.e., a form of repetitive negative thinking and a well-established vulnerability factor for depression) and regret (i.e., negative emotions containing self-blame, connected to cognitions about how past personal actions might have achieved better outcomes). However, these relations have not yet been investigated in experimental designs, and it has not been investigated how regret is related to both trait and state components of rumination. Therefore, in the present study we examined the temporal dynamics of repetitive negative thinking (state) in relation to regret, and how this is affected by interindividual differences in tendencies to engage in ruminative brooding (trait). Healthy females (N = 69) performed a sequential risk-taking task which included counterfactual feedback about alternative personal choice outcomes, and in which they experienced goal nonattainment (i.e., no monetary reward). Repetitive negative thoughts (state) prior to the task, and the tendency for ruminative brooding (trait), were both independently associated with reported regret after goal nonattainment, suggesting that both state and trait components of repetitive negative thinking render individuals more prone to experience regret. Furthermore, there was an interaction between regret after goal nonattainment and brooding (trait), in the sense that regret contributed to increases in (state) repetitive negative thinking, only among high brooders. The current results suggest that, among brooding-inclined individuals, the experience of regret may be a specific mechanism in aggravating repetitive negative thinking, which in turn may contribute to the development of psychopathology