Malleability of the self: electrophysiological correlates of the enfacement illusion

Abstract

Self-face representation is fundamentally important for self-identity and self-consciousness. Given its role in preserving identity over time, self-face processing is considered as a robust and stable process. Yet, recent studies indicate that simple psychophysics manipulations may change how we process our own face. Specifically, experiencing tactile facial stimulation while seeing similar synchronous stimuli delivered to the face of another individual seen as in a mirror, induces ‘enfacement’ illusion, i.e. the subjective experience of ownership of the other’s face and a bias in attributing to the self, facial features of the other person. Here we recorded visual Event-Related Potentials elicited by the presentation of self, other and morphed faces during a self-other discrimination task performed immediately after participants received synchronous and control asynchronous Interpersonal Multisensory Stimulation (IMS). We found that self-face presentation after synchronous as compared to asynchronous stimulation significantly reduced the late positive potential (LPP; 450–750 ms), a reliable electrophysiological marker of self-identification processes. Additionally, enfacement cancelled out the differences in LPP amplitudes produced by self- and other-face during the control condition. These findings represent the first direct neurophysiological evidence that enfacement may affect self-face processing and pave the way to novel paradigms for exploring defective self-representation and self-other interactions.

The enfacement illusion boosts facial mimicry

“…Our findings suggest that increased facial mimicry might be the 13 neurophysiological mechanism at the basis of initial evidence in favour of VT-IMS-induced emotional contagion and improved emotion recognition (Maister, Tsiakkas, & Tsakiris, 2013). The current study provides physiological evidence extending to the crucial social realm of emotions, the effects played by synchronous VT-IMS on self-identity representation (Bufalari, Sforza, Di Russo, Mannetti, & Aglioti, 2019;, tactile and proprioceptive perception Maister, Cardini, Zamariola, Serino, & Tsakiris, 2015), attention (Porciello et al, 2014) and social behaviour (Maister, Slater, Sanchezvives, & Tsakiris, 2015;Paladino et al, 2010).…”

“…To overcome this possible limitation, future studies with clinical populations could employ multiple VT-IMS sessions or couple VT-IMS with non-invasive brain stimulation(Antal et al, 2017;Rossi, Hallett, Rossini, Pascual-Leone, & Group, T. S. of T. C, 2009). This could be used to increase susceptibility of the neural substrates underlying visuo-tactile interpersonal multisensory integration and/or the blurring of self-other boundaries during the enfacement illusion(Apps, Tajadura-Jiménez, Sereno, Blanke, & Tsakiris, 2015;Bufalari, Sforza, Di Russo, , Project administration, Investigation, Data curation, Formal analysis, Writing-original draft. GP: Investigation, Formal analysis, Visualization, Writing -review & editing.…”

Fluid face but not gender: Enfacement illusion through digital face filters does not affect gender identity

“…To achieve the enfacement illusion most studies have used either real people [ 8 , 15 , 16 , 40 , 41 ], images or videos of real people, self-other face morphs [ 14 ] or computer-generated avatars [ 18 ]. In contrast to these stimuli and tools developed ad hoc by researchers and accessible only in a laboratory setting, we used widely accessible and popular social media face filters (Snap Inc., Santa Monica, CA).…”

Look at me now! Enfacement illusion over computer-generated faces

“…The literature reports different enfacement illusion paradigms. Some authors used two people sitting in front of each other ( Sforza et al, 2010 ; Bufalari et al, 2019 ) others used movies displaying real unfamiliar faces ( Tsakiris, 2008 ; Tajadura-Jiménez et al, 2012b ; Panagiotopoulou et al, 2017 ; Gülbetekin et al, 2021 ) or humanoid animated characters ( Gonzalez-Franco et al, 2020 ). More recently, the enfacement literature introduced the use of the 3-D personalized reconstruction of faces ( Grewe et al, 2021 ) and other standardized avatars ( Serino et al, 2015 ).…”