Guterstam Arvid, Larsson Dennis E O, Szczotka Joanna, Ehrsson H Henrik
Department of Psychology, Princeton University, Princeton, NJ, USA.
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
R Soc Open Sci. 2020 Dec 9;7(12):201911. doi: 10.1098/rsos.201911. eCollection 2020 Dec.
Previous research has shown that it is possible to use multisensory stimulation to induce the perceptual illusion of owning supernumerary limbs, such as two right arms. However, it remains unclear whether the coherent feeling of owning a full-body may be duplicated in the same manner and whether such a dual full-body illusion could be used to split the unitary sense of self-location into two. Here, we examined whether healthy human participants can experience simultaneous ownership of two full-bodies, located either close in parallel or in two separate spatial locations. A previously described full-body illusion, based on visuo-tactile stimulation of an artificial body viewed from the first-person perspective (1PP) via head-mounted displays, was adapted to a dual-body setting and quantified in five experiments using questionnaires, a behavioural self-location task and threat-evoked skin conductance responses. The results of experiments 1-3 showed that synchronous visuo-tactile stimulation of two bodies viewed from the 1PP lying in parallel next to each other induced a significant illusion of dual full-body ownership. In experiment 4, we failed to find support for our working hypothesis that splitting the visual scene into two, so that each of the two illusory bodies was placed in distinct spatial environments, would lead to dual self-location. In a final exploratory experiment (no. 5), we found preliminary support for an illusion of dual self-location and dual body ownership by using dynamic changes between the 1PPs of two artificial bodies and/or a common third-person perspective in the ceiling of the testing room. These findings suggest that healthy people, under certain conditions of multisensory perceptual ambiguity, may experience dual body ownership and dual self-location. These findings suggest that the coherent sense of the bodily self located at a single place in space is the result of an active and dynamic perceptual integration process.
先前的研究表明，利用多感官刺激诱发拥有多余肢体（如两条右臂）的感知错觉是有可能的。然而，尚不清楚是否能够以同样的方式复制拥有完整身体的连贯感觉，以及这种双重全身错觉是否可用于将单一的自我定位感一分为二。在此，我们研究了健康人类参与者是否能体验到同时拥有两个完整身体的感觉，这两个身体要么彼此平行且位置相近，要么处于两个不同的空间位置。一种先前描述的基于通过头戴式显示器从第一人称视角（1PP）对人造身体进行视觉 - 触觉刺激的全身错觉，被改编用于双身体设置，并在五个实验中通过问卷、行为自我定位任务和威胁诱发的皮肤电反应进行量化。实验1 - 3的结果表明，从彼此平行相邻的1PP视角对两个身体进行同步视觉 - 触觉刺激会诱发显著的双重全身所有权错觉。在实验4中，我们未能找到支持我们工作假设的证据，即把视觉场景一分为二，使两个错觉身体分别置于不同的空间环境中，会导致双重自我定位。在最后的探索性实验（实验5）中，我们通过使用两个人造身体的1PP之间的动态变化和/或测试房间天花板上的共同第三人称视角，找到了双重自我定位和双重身体所有权错觉的初步证据。这些发现表明，在多感官感知模糊的某些条件下，健康人可能会体验到双重身体所有权和双重自我定位。这些发现表明，在空间中单一位置的身体自我的连贯感觉是一个活跃且动态的感知整合过程的结果。
