Enhancing Multisensory Virtual Reality Environments through Olfactory Stimuli for Autobiographical Memory Retrieval

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors present the design of their equipment and a qualitative report of the five subjects who participated in a study, associated with the Faculty of Engineering in Foreign Languages, National University of Science and Technology Politechnica Bucharest, Romania, examining olfactory stimuli regarding autobiographical memory retrieval in virtual reality environments.

 

By their writing style, it is evident that the authors are excited by their product design and the results. They claim their work is the first of its kind. That is possible. However, to demonstrate this, the authors must examine other research in this area to determine how their work compares with similar work. The paper needs English editing as the phrasing is sometimes too colloquial. A substantial problem is that the manuscript neglects the journal requirements. The line-by-line suggested edits below indicate where changes will be needed.

 

Line by line suggested edits.

15-33 Abstracts are to be 200 words maximum—this Abstract is 246 words. Please reduce the Abstract. One aspect of reducing the number of words is deleting this information: “The research in this paper was done under Romanian Arut Research Grant no. 27/09/10/2023 ”Intelligent VR system for treating autobiographical/episodic memory deficits".

39-41 Please provide a recent peer-reviewed study to support the claim of this sentence.

39-56 To this point in the Introduction, all citations have been to outdated information. Please provide supporting citations published since 2020.

56 Please define “haptic stimuli” and a citation for this definition. 

62 Please add a paragraph examining past research on odor as having the most effective psychological impact when combined with VR. Here is a Google Scholar search that may be helpful in this regard: https://scholar.google.ca/scholar?hl=en&as_sdt=0%2C5&q=combining+VR+with+odor+may+have+the+most+effective+psychological+impact+&btnG=

65-68 Conducting the review of the research presented in the abovementioned Google Scholar search will determine if the authors are correct that their study is the first to add olfactory stimulation and, if so, what is different about their study that makes it unique.

76-78 Please delete this paragraph. It is unnecessary.

80-428 As per the Instructions for Authors (https://www.mdpi.com/journal/applsci/instructions), the manuscript must include these headings: Introduction, Materials and Methods, Results, Discussion, and Conclusions. The authors have an Introduction, Results, and Conclusions section. However, the Materials and Methods section and Discussion section are unused. Please restructure and rewrite this work to follow the organization required by this journal.

82-111 None of the studies cited in this section are to research published within the last five years. Please find supporting citations published since 2020 for each of the citations.

84-85 As the authors refer to “Studies”, please cite these studies.

97 Please define “Haptic feedback technology” and provide a supporting citation for this definition.

115 “Several” means more than two. Please cite at least one more reference to support this claim. It is best if the reference is from the last five years.

155-202 The focus of this paper is olfactory stimuli. Therefore, this section must concentrate on olfactory stimuli, briefly mentioning others, rather than giving all stimuli equal weight in the explanation. Furthermore, although citations 16, 22, and 24 are to current research, the rest of those cited in this section are not. Please find current supporting references to cite in conjunction with those citations that are outdated.

219 Please find a current supporting reference for citation 25.

221 &241 Please combine Figure 1 and Figure 2 so that Figure 1 represents a 2D drawing and Figure 2 the 3D rendering.

256 Please indicate that the VR interaction of Figure 3 represents what participants view while interacting.

258 “The WebXR library is mandatory for any VR WEBGL project”—please cite a current reference to support this claim.

276 & 284 Please indicate that when viewing the menu for Figure 4 and Figure 5, the participant is not interacting with the scene.

354 Please provide an undistorted, higher-resolution photo.

356 Please indicate what both people in the photo are doing. If both use the VR System, explain why only one has the headset.

404 Please provide current supporting evidence for citation 17.

442 Change “As far as we know nobody done this up to now” to “As far as we know we are the first to conduct this research”. The authors will determine if they are the first by examining the Google Scholar search provided by the reviewer.

464-465 Please move this statement to line 476 and add the heading “Institutional Review Board Statement:”. After this statement, please also add “Informed Consent Statement:” and provide the information given in the Supplementary files. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).

485-543 Please redo the references in MDPI style. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).

Comments on the Quality of English Language

The comments on the quality of English have been provided in the Comments and Suggestions for Authors.

Author Response

Dear Reviewer,

Thank you for the detailed and constructive review of our manuscript. We have considered all the comments and made the necessary revisions to the document. Below, you will find our responses to each comment.

Comments 1: 15-33 Abstracts are to be 200 words maximum—this Abstract is 246 words. Please reduce the Abstract. One aspect of reducing the number of words is deleting this information: “The research in this paper was done under Romanian Arut Research Grant no. 27/09/10/2023 ”Intelligent VR system for treating autobiographical/episodic memory deficits".

Response: Thank you for your feedback regarding the abstract length. We have revised the abstract to comply with the 200 words limit. As suggested, we have removed the information regarding th research grant.

Comments 2: 39-41 Please provide a recent peer-reviewed study to support the claim of this sentence.

Response: In response to your request, we have included a more recent peer-reviewed study to support the claim in the sentence. We have introduced the following reference to the existing text: "Seitz, A.R., Kim, R., & Shams, L. (2006). Sound facilitates visual learning. Curr Biol. 16(14):1422-7. doi: 10.1016/j.cub.2006.05.048."

Comments 3: 39-56 To this point in the Introduction, all citations have been to outdated information. Please provide supporting citations published since 2020.

Response: Regarding the citations in the Introduction section. We understand the importance of using current sources to support our research. In response to your suggestion, we have included several recent references published since 2020 to strengthen the article. These updated references can be found in the revised version of the manuscript

Comments 4: 56 Please define “haptic stimuli” and a citation for this definition. 

Response: To address your comment, we have defined "haptic stimuli" :

"In this experiment, they use as tactile stimulus, artificial grass made of plastic and synthetic materials with a thick and abundant texture which make the tactile sensation as similar to natural grass as possible".

Comments 5: 62 Please add a paragraph examining past research on odor as having the most effective psychological impact when combined with VR. Here is a Google Scholar search that may be helpful in this regard: https://scholar.google.ca/scholar?hl=en&as_sdt=0%2C5&q=combining+VR+with+odor+may+have+the+most+effective+psychological+impact+&btnG=

Response: An important question remains whether the addition of multi sensory components changes or amplifies the effect obtained through simple VR. Hence, in a review from 2021, one of the most important authors from the field of oder-evoked autobiographical memory, Rachel Hertz, presents how olfaction could be incorporated into VR technology to be make it a more efficient intervention. She noted that although VR technology has already been successfully used to treat PTSD, it has not been associated with odor. The author proposes as a possible intervention the coupling of VR with odor and the use of this combination for the reappraisal of a traumatic memory. She proposed that due to the uniquely emotional features of olfactory processing and odor-evoked memory, olfaction combined with VR is excellent positioned to be effectively used in the treatment of this disorder. However, until now, we have not found a practical implementation of this proposal.  

Comments 6:65-68 Conducting the review of the research presented in the above mentioned Google Scholar search will determine if the authors are correct that their study is the first to add olfactory stimulation and, if so, what is different about their study that makes it unique.

Response: Continuing the line of studies carried out by us previously [10, 11] in this paper, we present a VR system together with an odor device for autobiographical memory retrieval, but, this time, using a qualitative analysis. To the best of our knowledge, we are the first from this series of experiments to add ol-factory stimulation (thus representing a mixed reality procedure) and offer the partici-pants the opportunity to interact with the virtual environment manipulating virtual objects with their virtual hands. This is an advancement to what exists currently and original research elements for our paper. Also, given that we use a qualitative analysis of the results, this study can surprise to a greater extent the emotional experiences of the participants. This we consider another novelty of the research reported in this paper - as most of the published research for such systems is quantitative in nature.

Comments 7: 76-78 Please delete this paragraph. It is unnecessary.

Response: This entire paragraph was re-writen.

Comments 8: 80-428 As per the Instructions for Authors (https://www.mdpi.com/journal/applsci/instructions), the manuscript must include these headings: Introduction, Materials and Methods, Results, Discussion, and Conclusions. The authors have an Introduction, Results, and Conclusions section. However, the Materials and Methods section and Discussion section are unused. Please restructure and rewrite this work to follow the organization required by this journal.

Response: We have revised the manuscript to include all the required headings as per the Instructions for Authors. The updated manuscript now includes the following sections: Introduction, Materials and Methods, Results, Discussion, and Conclusions.

Comments 9:  82-111 None of the studies cited in this section are to research published within the last five years. Please find supporting citations published since 2020 for each of the citations.

Response: We have included several recent references published since 2020 to strengthen the article. These updated references can be found in the revised version of the manuscript.

Comments 10: 84-85 As the authors refer to “Studies”, please cite these studies

Response: In the continuation of the paragraph, these studies are cited.

Comments 11: 97 Please define “Haptic feedback technology” and provide a supporting citation for this definition.

Response: We have defined "Haptic feedback technology" and provided a supporting citation. This definition will be included in the revised version of the manuscript.

Comments 12: 115 “Several” means more than two. Please cite at least one more reference to support this claim. It is best if the reference is from the last five years.

Response: We have added an additional reference to support the claim and ensure it is well-supported. The references now include recent studies from the last five years.

Comments 13: 155-202 The focus of this paper is olfactory stimuli. Therefore, this section must concentrate on olfactory stimuli, briefly mentioning others, rather than giving all stimuli equal weight in the explanation. Furthermore, although citations 16, 22, and 24 are to current research, the rest of those cited in this section are not. Please find current supporting references to cite in conjunction with those citations that are outdated.

Response: We have revised the section to focus primarily on olfactory stimuli, briefly mentioning other types of stimuli. Additionally, we have included current supporting references to replace the outdated ones.

Comments 14: 219 Please find a current supporting reference for citation 25.

Response: We have updated citation 25 with a more current reference to support the claim. The new reference is: 33. Leiker, E.K., Riley, E., Barb, S., Lazzaro, S.K., Compère, L., Webb, C., Canovali, G. and Young, K.D. (2024). Recall of Autobio-graphical Memories Following Odor vs Verbal Cues Among Adults With Major Depressive Disorder. JAMA Network Open, 7 (2): e2355958 DOI: 10.1001/jamanetworkopen.2023.55958

Comments 15: 221 &241 Please combine Figure 1 and Figure 2 so that Figure 1 represents a 2D drawing and Figure 2 the 3D rendering.

Response: We have combined Figure 1 and Figure 2 as requested. Now, Figure 1 represents odor dispenser mechanism 2D and 3D rendering. These changes have been reflected in the updated manuscript.

Comments 16: 256 Please indicate that the VR interaction of Figure 3 represents what participants view while interacting.

Response: We have updated the caption of Figure 3 to indicate that it represents what participants view while interacting in the VR environment.

Comments 17: 258 “The WebXR library is mandatory for any VR WEBGL project”—please cite a current reference to support this claim.

Response: To support the claim that the WebXR library is mandatory for any VR WEBGL project, we have included a current reference. The WebXR Device API is essential for building VR and AR applications on the web, providing a platform-independent interface to access VR hardware and render immersive virtual graphics (Machines, 2023; Applied Sciences, 2023).

Comments 18: 276 & 284 Please indicate that when viewing the menu for Figure 4 and Figure 5, the participant is not interacting with the scene.

Response: We have updated the captions for Figures 4 and 5 to clarify that when viewing the menu, participant is not interacting with the scene.

Comments 19: 354 Please provide an undistorted, higher-resolution photo.

Response: We have modified the photo to provide an undistorted, higher-resolution version. The updated photo is included in the revised manuscript.

Comments 20: 356 Please indicate what both people in the photo are doing. If both use the VR System, explain why only one has the headset.

Response: Wearing the VR headset on the head is a participant who recalls an autobiographical episode while the experimenter follows on the screen the image that the subject sees in the VR headset.

Comments 21: 404 Please provide current supporting evidence for citation 17.

Response: We have provided current supporting evidence for citation 17 to ensure that the claim is well-supported by recent literature.

Comments 22: Change “As far as we know nobody done this up to now” to “As far as we know we are the first to conduct this research”. The authors will determine if they are the first by examining the Google Scholar search provided by the reviewer.

Response: We have revised the sentence to reflect that, to the best of our knowledge, we are the first to conduct this research. Additionally, we have examined the Google Scholar search you provided to ensure the originality of our study.

Comments 23: 464-465 Please move this statement to line 476 and add the heading “Institutional Review Board Statement:”. After this statement, please also add “Informed Consent Statement:” and provide the information given in the Supplementary files. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).

Response: We send the Ethical Approval and the Informed Consent.

Comments 24: 485-543 Please redo the references in MDPI style. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).

Response: We have reformatted the references according to the MDPI style guidelines.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Sirs,

Thank you for this opportunity to review the manuscript. It's really very interesting.

I would like to highlight the importance of indicating the registration code of the study protocol in the abstract of the article and in the main text.

It is important in general to expand the bibliographic references that support the research with scientific evidence, since only 26 references are presented, which are scarce to support this type of study.

It would be interesting to clarify the objectives of this study and what the described effects are intended to achieve.

Regarding the methodology, the sample of participants and other aspects such as the calculation of the sample to carry out the study are not clear.

It is important to indicate how the qualitative methodology indicated in the study was carried out, whether by providing the questions that were asked to the patients, the use of a standardized instrument, sample recruitment, etc...

Regarding the images that the authors present in the manuscript, it is important that the source be indicated or if it is their own creation.

 

It would be advisable, for example, for section 2.1 to indicate more scientific evidence on VR in autobiographical memories; only two studies are indicated.

 

 

Discussion

It would be highly recommended to indicate whether other techniques have been effective or not in this area.

 

In the final section, indicate the ethical committee that approved the research. The ethical aspects are missing.

Author Response

Thank you for the detailed and constructive review of our manuscript. We have considered all the comments and made the necessary revisions to the document. Below, you will find our responses to each comment.

We uploaded the response.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you to the authors for the changes they have made to their manuscript. Some have improved it. Further changes are below.

 

Line by line suggested edits.

15-31 Although the Abstract is no longer 246 words, at 223 words, it is still not within the 200-word limit. Please rewrite the Abstract and reduce the words to 200.

41 The authors claim they have provided a current reference for citation 2. The reference is from 2006. Current means since 2020. Please find a current reference.

54 The authors state in their response to the reviewer: “We have defined "Haptic feedback technology" and provided a supporting citation. This definition will be included in the revised version of the manuscript.” There is no definition provided, nor is there a supporting citation. Correct this.

68 Until this line, all the citations are outdated. If the authors cannot find current research to cite, they must include the year the cited work was published in the text. This means including the year for citations 1-7.

77 Change “to be make it” to “to make it”.

80 Change “the coupling of VR with odor” to “coupling VR with odor”.

85-101 As all these citations are outdated, the authors must include the year the work was published in the text.

119 There is no citation 19. Please insert citation 19. Citation 22 is mentioned before citation 21 (appearing in line 159).

201 Citation 32 comes before citations 29-31.  Correct this.

233-235 Please interchange the pictures so that the 2D rendering comes before the 3D one.

270 Although the authors have cited research in their response to the reviewer regarding the claim concerning the WebXR library, these citations are not part of the text nor in the reference list. Please include the citations in the text and add the research to the reference list.

290-296 Please switch these lines to format for one line rather than one and a half.

326 Citation 34 comes before citation 33, which appears in line 442. Furthermore, the publication date for the “existing literature” must be provided since it is not current research.

328 It is unclear why the authors have considered it necessary to add an Appendix. It is unnecessary. If they want to continue to include an appendix, the one item in the Appendix must be numbered and cited as Appendix 1.

375-410 The Results must refer to the various figures. Please include the results regarding the Figures. The authors must also provide a table indicating the results for each participant and refer to this table in the text.

412 Change “Discussions” to “Discussion”.

497 In the previous review, the reviewer stated “add the heading “Institutional Review Board Statement:”. After this statement, please also add “Informed Consent Statement:” and provide the information given in the Supplementary files. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).” The authors have not done either of these things. Correct this.

503-604 The authors have redone their reference list, but not in MDPI style. Please refer to the Instructions for Authors and redo the reference list appropriately.

611 Please number the Appendix.

Comments on the Quality of English Language

The comments on the quality of English have been provided in the Comments and Suggestions for Authors.

Author Response

Dear Reviewer ,

Thank you again for your comments.

Line by line suggested edits.

Q1:15-31 Although the Abstract is no longer 246 words, at 223 words, it is still not within the 200-word limit. Please rewrite the Abstract and reduce the words to 200.

R1:The abstract was reduced to 199 words.

 

Q2:41 The authors claim they have provided a current reference for citation 2. The reference is from 2006. Current means since 2020. Please find a current reference.

R2:The year was added in front of the reference as per recommendation from Q4.

 

Q3:54 The authors state in their response to the reviewer: “We have defined "Haptic feedback technology" and provided a supporting citation. This definition will be included in the revised version of the manuscript.” There is no definition provided, nor is there a supporting citation. Correct this.

R3:Haptic feedback is described in reference 6, it refers to mimicking the sense of touching an object. “Serrano et al. [6]used VR images, odors, and haptic stimuli individually”,  line 52.

 

Q4:68 Until this line, all the citations are outdated. If the authors cannot find current research to cite, they must include the year the cited work was published in the text. This means including the year for citations 1-7.

R4: For the citations 1-6 the year was added in front of them, for number 7, the work is from 2021.

 

Q5:77 Change “to be make it” to “to make it”.

R5:The change was made according to the suggestion.

 

Q6:80 Change “the coupling of VR with odor” to “coupling VR with odor”.

R6:The change was made according to the suggestion.

 

Q7:85-101 As all these citations are outdated, the authors must include the year the work was published in the text.

R7: For the references 10,11,12,13, 15, 16, 17, 22,23,24,25,26, 28,33 the year the work was published was added in the text.

Q8:119 There is no citation 19. Please insert citation 19. Citation 22 is mentioned before citation 21 (appearing in line 159).

R8: reference 19 was inserted at line 117 ( it replaced the reference 22), now they are in order.

Q9:201 Citation 32 comes before citations 29-31.  Correct this.

R9: The order of the references was changed.

Q10:233-235 Please interchange the pictures so that the 2D rendering comes before the 3D one.

R10: The figure description was changed to correspond the figure image :

“Odor Dispenser Mechanism 3D and 2D rendering”

Q11:270 Although the authors have cited research in their response to the reviewer regarding the claim concerning the WebXR library, these citations are not part of the text nor in the reference list. Please include the citations in the text and add the research to the reference list.

R11: The text was reformulated to remove the appearance of a claim on line 268 : 

“The WebXR library was used for the web implementation of the VR WEBGL project because……”

Q12:290-296 Please switch these lines to format for one line rather than one and a half.

R12:The change was made according to the suggestion.

 

Q13:326 Citation 34 comes before citation 33, which appears in line 442. Furthermore, the publication date for the “existing literature” must be provided since it is not current research.

R13:The order of the references was corrected.

Q14: 328 It is unclear why the authors have considered it necessary to add an Appendix. It is unnecessary. If they want to continue to include an appendix, the one item in the Appendix must be numbered and cited as Appendix 1.

R14:Appendix was removed

 

Q15:375-410 The Results must refer to the various figures. Please include the results regarding the Figures. The authors must also provide a table indicating the results for each participant and refer to this table in the text.

R15: References to the figures were added in the Results section. Regarding the table we are sorry, but in different previous articles of this kind that we published we reported the results as in this one and we want to keep it this way also for the current one (we think that this suits better the privacy of the participants). We hope for reviewer understanding

 

Q16:412 Change “Discussions” to “Discussion”.

R16: The change was made according to the suggestion.

Q17:497 In the previous review, the reviewer stated “add the heading “Institutional Review Board Statement:”. After this statement, please also add “Informed Consent Statement:” and provide the information given in the Supplementary files. Please see the Instructions for Authors for further guidance (https://www.mdpi.com/journal/applsci/instructions).” The authors have not done either of these things. Correct this.

R17: The 2 section were added in the paper after line 497.

 

Q18:503-604 The authors have redone their reference list, but not in MDPI style. Please refer to the Instructions for Authors and redo the reference list appropriately.

R18:MDPI reference style was applied to the references

Q19:611 Please number the Appendix.

R19:The Appendix was removed as per previous recommendations.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors, 

Congratulations for the improvement of the article. 

Kind regards, 

 

Author Response

Dear Reviewer,

Thank you very much for your kind words and for recognizing the improvements in the article. We appreciate your feedback and support.

 

Kind regards,