Embodiment Is Related to Better Performance on a Brain–Computer Interface in Immersive Virtual Reality: A Pilot Study

Round 1

Reviewer 1 Report

The manuscript offers interesting insights on how the sense of embodiment is linked to an increase neurofeedback performance in healthy individuals. Their results suggest that neurofeedback presented in a first-person perspective in HMD-VR may increase one’s feeling of embodiment compared to neurofeedback presented on a computer screen (lines 352-353). To support further their findings, more research must be done, by involving users with disability (i.e. stroke victims, etc) and with larger numbers of participants. In general, the study read well. My expertise and background are related to the psychology behind the notion of embodiment. In that respect, the article needs couple of minor precisions. Below I suggest points of improvement. After considering these points, the manuscript will be ready for publication, in my opinion.

 

General point: To help readers to familiarize themselves with the notion of embodiment, authors should consider detailing further why the concept of embodiment is essential for neurofeedback. On line 50, the authors suggest BCI are designed to attempt to close the loop between motor commands and sensory feedback. May the authors add one or two lines explaining why embodiment is crucial to experience feeling of being in the loop. Why not notion of agency? Authors define embodiment (lines 67-69) “as the perceptual ownership of a virtual body in a virtual space 68”. Embodiment is complex as it includes not only perceptual ownership over virtual body, but also agency, control, especially via BCI. To enhance the various dimension of BCI embodiment, authors should refer to report of users experiencing embodiment via BCI control. For example Gilbert, F., Cook, M., O’Brien, T. et al.Embodiment and Estrangement: Results from a First-in-Human “Intelligent BCI” Trial. Sci Eng Ethics 25, 83–96 (2019) doi:10.1007/s11948-017-0001-5 Line 130, authors indicate the study was interested in looking at C1, C3 and CP1. A quick allusion to why these 3 variables were rather the focus would help readers not familiar with these brain activities. Line 361, the word “individuals.” is repeated. Remove the last one. Section 4.5. The authors discuss the design behind REINVENT. Is it possible to anticipate what psychologically may happen to users not experiencing embodiment? May it induce a phenomenology opposite of embodiment? Alienation or estrangement? As a result, could it lead to a slow or even difficult recovery?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thank you for allowing me to review this manuscript. The purpose of this study was to compare neurofeedback performance in HMD-VR versus a computer screen in twelve healthy individuals and examined individual differences in some measures. This study is relevant and useful in a number of ways, but specifically in develops Virtual Reality treatment possibilities and research.

The manuscript shows relevance and interest. The issue has interest for students and professionals. The present study attempted to address an important, interesting, cognitive research applied and timely question. There are multiple positive aspects within the manuscript were identified.

However, I have some comments that the authors might want to consider. However, there is overall lack of virtual reality literature review presentation, some problems about research analysis. Also, manuscript and the authors should pay great attention to actual literature state of art of virtual possibilities (much of them it is not international or general). Much of the Introduction appears tangential to the central thrust of the authors' findings and there is no guiding theoretical framework. Also, is necessary to specify clearly the contribution of the work.

 

Please check and review Figures legends description, some results are there (e.g. Figure 6). They are morass and some information duplicate. It would be necessary to report more clearly, how the data were recruited in a Procedure section; information does not help to understand the study. Instruments have to be more described (reliability and validity measures in quetionaires). Interpretation of the measures. The specific variables taken into account. The variables under study are not clear. Also, the instruments and theoretical models have to be explained previously and have to be justified in the introduction section. Age and gender could be control variables in the analysis strategy. Please include ethical principles in this research.

 

Results

Results are extensive showed in this section. A subheading for every analysis or hypothesis is helpful. Please include asymmetry and skewness values, necessary to develop parametric analysis. Authors present Shapiro-Wilk test in 3.5 subheading. Please include means and SD in a table of all the variables. In the results, the authors don`t report differences between control variables (e.g. gender, age etc..). This is important to discuss in implications for practices. Also, reformulate analysis strategy for the hypothesis and the results. Correlations before regression results could be suitable to improve the aims of this study. In the results section, text results´ interpretations are presented and it has to move for discussion section. Some of them in Figures legends. Please explain the mean of the t de student test and direction and include effect size.

Discussion

The manuscript has important implications (for research future) that are well described. As noted earlier, the authors should discuss the results in relation to a theoretical framework. Last but not least, the discussion section does a good job in summarizing the results but as we advance toward the conclusions (just a few old cites in discussion section). Structure of the discussion is difficult to understand, could be more fitting follow the same structure as in the presentation of results. The In general, must be clear the contribution of the work to the subject matter of study.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf