de Jong Jutta R, Keizer Anouk, Engel Manja M, Dijkerman H Chris
Experimental Psychology/Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.
Exp Brain Res. 2017 Jun;235(6):1781-1791. doi: 10.1007/s00221-017-4912-9. Epub 2017 Mar 13.
The sense of how we experience our physical body as our own represents a fundamental component of human self-awareness. Body ownership can be studied with bodily illusions which are generated by inducing a visuo-tactile conflict where individuals experience illusionary ownership over a fake body or body part, such as a rubber hand. Previous studies showed that different types of touch modulate the strength of experienced ownership over a rubber hand. Specifically, participants experienced more ownership after the rubber hand illusion was induced through affective touch vs non-affective touch. It is, however, unclear whether this effect would also occur for an entire fake body. The aim of this study was, therefore, to investigate whether affective touch modulates the strength of ownership in a virtual reality full body illusion. To elicit this illusion, we used slow (3 cm/s; affective touch) and fast (30 cm/s; non-affective touch) stroking velocities on the participants' abdomen. Both stroking velocities were performed either synchronous or asynchronous (control condition), while participants viewed a virtual body from a first-person-perspective. In our first study, we found that participants experienced more subjective ownership over a virtual body in the affective touch condition, compared to the non-affective touch condition. In our second study, we found higher levels of subjective ownership for synchronous stimulation, compared to asynchronous, for both touch conditions, but failed to replicate the findings from study 1 that show a difference between affective and non-affective touch. We, therefore, cannot conclude unequivocally that affective touch enhances the full-body illusion. Future research is required to study the effects of affective touch on body ownership.
我们如何将自己的身体体验为属于自己的这种感觉，是人类自我意识的一个基本组成部分。身体所有权可以通过身体错觉来研究，这些错觉是通过引发视觉 - 触觉冲突产生的，在这种冲突中，个体对一个假的身体或身体部位，比如一只橡胶手，会产生错觉性的所有权。先前的研究表明，不同类型的触摸会调节对橡胶手体验到的所有权的强度。具体来说，在通过情感触摸而非非情感触摸诱发橡胶手错觉后，参与者会体验到更强的所有权。然而，尚不清楚这种效应对于整个假身体是否也会出现。因此，本研究的目的是调查情感触摸是否会调节虚拟现实全身错觉中所有权的强度。为了引发这种错觉，我们在参与者的腹部使用了缓慢（3厘米/秒；情感触摸）和快速（30厘米/秒；非情感触摸）的抚摸速度。两种抚摸速度都以同步或异步（对照条件）的方式进行，同时参与者从第一人称视角观看一个虚拟身体。在我们的第一项研究中，我们发现与非情感触摸条件相比，参与者在情感触摸条件下对虚拟身体体验到了更多的主观所有权。在我们的第二项研究中，我们发现对于两种触摸条件，与异步刺激相比，同步刺激下的主观所有权水平更高，但未能重复第一项研究中显示情感触摸和非情感触摸之间存在差异的结果。因此，我们不能明确得出情感触摸会增强全身错觉的结论。未来的研究需要探讨情感触摸对身体所有权的影响。
