Measurement of the Permissible Range of Consistency between Visual and Tactile Presentations of Line Grating Textures

Round 1

Reviewer 1 Report

The authors aim to measure the inconsistency between visual and tactile stimuli, more precisely the permissible range associated with 1-dimension real textures. Although with the same subject, this paper seems to be an improvement over their initial study presented in [18]. The experiment setup uses the holographic effect to superimpose visual cues over the real texture.

1. In the Abstract section, you should stick to the advances brought by your research, and leave future developments aside "Our future work will include tests with wider texture range and two-dimensional 22 textures."
2. "A method that uses a real object for haptic presentation can present haptics comparable to reality. Because it is difficult to synthetically reproduce textures such as rough and slippery textures, this method is more suitable for a system that emphasizes texture." -> this paragraph is not clear and should be rewritten
3. The sizes of ridges and grooves seem to be arbitrary. Could you expand on why you've chosen the dimensions presented in the paper?
4. Fig. 1b should present the smartphone screen. I can't see the black&white stripes.
5. The findings are a bit "scarce". In my opinion, it is obvious that the normalized threshold is larger for textures with a smaller spatial period. What is more interesting is the correlation between the force and the position of the finger, and the activity of sensing the texture. This, unfortunately, is only mentioned by the authors as future work.

Author Response

Thank you so much for the valuable comments and suggestions. The following are our responses.

1. In the Abstract section, you should stick to the advances brought by your research, and leave future developments aside "Our future work will include tests with wider texture range and two-dimensional 22 textures."
   -Response: We corrected this point in revised manuscript. Please refer to L22.
   
   
2. "A method that uses a real object for haptic presentation can present haptics comparable to reality. Because it is difficult to synthetically reproduce textures such as rough and slippery textures, this method is more suitable for a system that emphasizes texture." -> this paragraph is not clear and should be rewritten
   -Response: We corrected this point in revised manuscript. Please refer to L40-41.
   
   
3. The sizes of ridges and grooves seem to be arbitrary. Could you expand on why you've chosen the dimensions presented in the paper?
   -Response: The following factors determine the size of ridges and grooves.
        ・The lowest width (0.2 mm) is limit that the 3D printer used for texture creation can accurately shape the ridges and grooves of  square wave.
        ・In previous report, we found there is permissible range of 0.4 mm or more for each condition of the reference stimulus, so we changed the size of the reference stimulus at 0.4 mm intervals.
        ・The maximum value of ridges and grooves (3.0mm) was provisional, and we were planning to consider whether or not it should be expanded based on the results of this experiment.
   The above factors were added to the revised manuscript in L124-130.
   
   
4. Fig. 1b should present the smartphone screen. I can't see the black&white stripes.
   -Response: We replaced Fig. 1(b) with new image.
   
   
5. The findings are a bit "scarce". In my opinion, it is obvious that the normalized threshold is larger for textures with a smaller spatial period. What is more interesting is the correlation between the force and the position of the finger, and the activity of sensing the texture. This, unfortunately, is only mentioned by the authors as future work.
   -Response:
   Thank you for your comment. In our experiment, we did not specify speed or pressure, intending to prepare natural situation. Consequently, the pressure and speed did not change so much among participants, and we could not find any tendency.
   

   On the other hand, we consider that our finding is not fully intuitive. If Weber’s law is applied, the normalized threshold should be constant. The decrease of normalized threshold when tactile texture becomes larger is also practically important for future application, since it means that the finer textures can be more “discretely” presented than rough textures. The tendency seems to stop from around 2mm texture, which is also interesting. We added text about the findings. Please refer to L253-256.
   

Reviewer 2 Report

General: it is an interesting paper, exploring the requirements for consistency of haptic presentations in combination with visual presentations in order to enhance experiencing VR.

Major short coming is that the trial was done with only 10 (+1) participants, thus limiting the solidity of the conclusions.

Suggestions to improve the paper. Figure 1 is not easy to understand and should be redone. Possibly a drawing for 1a instead of a photo, and showing the position of the participant. 1b a screenshot of the smartphone's display.

Sometimes the order of the text is not proper. lines 147-149 should come after line 155

Author Response

Thank you so much for the valuable comments and suggestions. The following are our responses.

Major short coming is that the trial was done with only 10 (+1) participants, thus limiting the solidity of the conclusions.
   -We are sorry for relatively small number of participants. It is currently difficult to recruit subjects due to the effects of the Covid-19 situation. 

Suggestions to improve the paper. Figure 1 is not easy to understand and should be redone. Possibly a drawing for 1a instead of a photo, and showing the position of the participant. 1b a screenshot of the smartphone's display.
  -We replaced Fig. 1(a) with new image, and corrected caption of Fig. 1(b).

Sometimes the order of the text is not proper. lines 147-149 should come after line 155
  -We corrected this point in revised manuscript. Please refer to L154, 156-157, 158.

Round 2

Reviewer 1 Report

Thank you for addressing the issue. I agree with the first reviewer, the number of subjects in relatively limited. However, the experiment methodology and the findings are interesting enough to be published.