Dissociating facial electromyographic correlates of visual and verbal induced rumination

Previous research showed that mental rumination, considered as a form of repetitive and negative inner speech, is associated with increased facial muscular activity. However, the relation between these muscular activations and the underlying mental processes is still unclear. In this study, we tried to separate the facial electromyographic correlates of induced rumination related to either i) mechanisms of (inner) speech production or ii) rumination as a state of pondering on negative affects. To this end, we compared two groups of participants submitted to two types of rumination induction (for a total of 85 female undergraduate students without excessive depressive symptoms). The first type of induction was designed to specifically induce rumination in a verbal modality whereas the second one was designed to induce rumination in a visual modality. Following the *motor simulation view* of inner speech production, we hypothesised that the verbal rumination induction should result in a higher increase of activity in the speech-related muscles as compared to the non-verbal rumination induction. We also hypothesised that relaxation focused on the orofacial area should be more efficient in reducing rumination (when experienced in a verbal modality) than a relaxation focused on a non-orofacial area. Our results do not corroborate these hypotheses, as both rumination inductions resulted in a similar increase of peripheral muscular activity in comparison to baseline levels. Moreover, the two relaxation types were similarly efficient in reducing rumination, whatever the rumination induction. We discuss these results in relation to the inner speech literature and suggest that because rumination is a habitual and automatic form of emotion regulation, it might be a particularly (strongly) internalised and condensed form of inner speech. Pre-registered protocol, preprint, data, as well as reproducible code and figures are available at: https://osf.io/c9pag/.

过往研究指出，沉思，作为一种重复且消极的内在言语形式，与面部肌肉活动增加相关。然而，这些肌肉活动与潜在心理过程之间的关系尚不明确。在本研究中，我们试图区分由沉思引发的面部肌电图（EMG）相关因素，这些因素可能与以下两种机制之一有关：i)（内在）言语产生的机制，或ii)沉思作为一种对负面情感的沉思状态。为此，我们比较了两组接受两种类型沉思诱导的参与者（总计85名无过度抑郁症状的女大学生）。第一种诱导旨在特定地通过言语模式诱导沉思，而第二种诱导则旨在通过视觉模式诱导沉思。根据内在言语生产的*运动模拟观*，我们假设言语沉思诱导应导致与言语相关肌肉活动增加高于非言语沉思诱导。我们还假设，针对口腔面部区域的放松应比针对非口腔面部区域的放松在减少沉思（在言语模式中体验）时更为有效。然而，我们的研究结果并未证实这些假设，因为两种沉思诱导均导致与基线水平相比外周肌肉活动增加相似。此外，两种放松类型在减少沉思方面的效率也相似，无论沉思诱导的方式如何。我们将这些结果与内在言语文献联系起来，并建议由于沉思是一种习惯性和自动化的情绪调节形式，它可能是一种特别（强烈）内化和浓缩的内在言语形式。预注册方案、预印本、数据以及可重复的代码和图表均可在以下链接获取：https://osf.io/c9pag/。