Because most humans live and work in populated environments, researchers recently took into account that people may not only experience first-hand stress, but also second-hand stress related to the ability to empathically share another person’s stress response. Recently, researchers have begun to more closely examine the existence of such empathic stress and highlighted the human propensity to physiologically resonate with the stress responses of others. As in case of first-hand stress, empathic stress could be deleterious for health if people experience exacerbated activation of hypothalamic–pituitary–adrenal and autonomic nervous systems. Thus, exploring empathic stress in an observer watching someone else experiencing stress is critical to gain a better understanding of physiological resonance and conduct strategies for health prevention. In the current study, we investigated the influence of empathic stress responses on heart rate variability (HRV) with a specific focus on nonlinear dynamics. Classic and nonlinear markers of HRV time series were computed in both targets and observers during a modified Trier social stress test (TSST). We capitalized on multiscale entropy, a reliable marker of complexity for depicting neurovisceral interactions (brain-to-heart and heart-to-brain) and their role in physiological resonance. State anxiety and affect were evaluated as well. While classic markers of HRV were not impacted by empathic stress, we showed that the complexity marker reflected the existence of empathic stress in observers. More specifically, a linear model highlighted a physiological resonance phenomenon. We conclude on the relevance of entropy in HRV dynamics, as a marker of complexity in neurovisceral interactions reflecting physiological resonance in empathic stress.

L’accessibilité Web a pour objectif de « mettre le Web et ses services à la disposition de tous les individus, quels que soient leur matériel ou logiciel, leur infrastructure réseau, leur langue maternelle, leur culture, leur localisation géographique et leurs aptitudes physiques » [Berners-Lee, 1996]. Des normes internationales comme le WCAG (Web Content Accessibility Guidelines) ou nationale comme le RGAA en France (Référentiel général d’accessibilité pour les administrations), décrivent les règles permettant de concevoir un site accessible. Malgré l’existence de ces normes, peu de sites Internet sont accessibles [Web Accessibility in European countries, 2009]. Il semble alors important de comprendre l’origine de ce blocage : pour quelles raisons les professionnels du Web ne conçoivent-ils pas davantage de sites respectant les règles d’accessibilité ? C’est le but de l’enquête que nous avons menée auprès de professionnels du Web afin d’identifier les principales pratiques en situation professionnelle et de découvrir la nature des freins concernant l’appropriation et le développement de l’accessibilité Web. Les résultats seront discutés au regard des représentations et des préjugés concernant l’accessibilité Web tels qu’ils sont partagés par les divers professionnels du Web.

Studies so far have analyzed the effect of distractor stimuli in different types of brain–computer interface (BCI). However, the effect of a background speech has not been studied using an auditory event-related potential (ERP-BCI), a convenient option when the visual path cannot be adopted by users. Thus, the aim of the present work is to examine the impact of a background speech on selection performance and user workload in auditory BCI systems. Eleven participants tested three conditions: (i) auditory BCI control condition, (ii) auditory BCI with a background speech to ignore (non-attentional condition), and (iii) auditory BCI while the user has to pay attention to the background speech (attentional condition). The results demonstrated that, despite no significant differences in performance, shared attention to auditory BCI and background speech required a higher cognitive workload. In addition, the P300 target stimuli in the non-attentional condition were significantly higher than those in the attentional condition for several channels. The non-attentional condition was the only condition that showed significant differences in the amplitude of the P300 between target and non-target stimuli. The present study indicates that background speech, especially when it is attended to, is an important interference that should be avoided while using an auditory BCI.