Hemifield-Specific Rotational Biases during the Observation of Ambiguous Human Silhouettes

Round 1

Reviewer 1 Report

This piece of research aims to examine how the lateralized presentation of an ambiguous rotating human body would affect its perceived handedness/footedness or both.

Thank you for inviting me to review this research. I would like to congratulate authors on this interesting and inspiring piece of research. I really enjoyed it and I am willing to read more from this front.

I only have two minor suggestions, up to the authors to consider them:

1. Review the abstract. Many information is focused in contextualising the topic, and less on the current results. It is a pity as authors have found nice results in the research.
2. Do you think that hand dominance (left-handedness or right-handedness) could be a variable to be taken into account?

Author Response

Point 1: Review the abstract. Many information is focused in contextualising the topic, and less on the current results. It is a pity as authors have found nice results in the research.


Response 1: We thank the Reviewer for her/his suggestion, and we have modified the abstract accordingly.

Point 2: Do you think that hand dominance (left-handedness or right-handedness) could be a variable to be taken into account?

Response 2: Similarly to our previous studies with ambiguous human silhouettes, the degree of participants’ handedness did not show a significant effect. Although in the previous version of the manuscript we mentioned this issue in the Introduction and Results sections, we omitted to further address it in the Discussion section. We thank the Reviewer for noticing this omission, which we have fixed in the revised manuscript (see the first and the fourth paragraph of the Discussion section).

Reviewer 2 Report

The paper overall is well written and strucctured. The experiment is pretty straight forward and clear. The authors report upon a study on the hemispheric bias in rotational perception. They also look at sex and handedness as moderators among others.Overall I recommend a minor revision for the article. Nevertheless I have some issues with the manuscript in its current state; please find them below in no particular order:

• The authors state in their abstract and other times in the manuscript that the indication of the spinning rotation (CW or CCW) indirectly also is linked to perceived handedness. Although I'd be inclined to believe the authors here, they did not ask participans for the perceived handedness and authors should be careful with statements like this.
• The power analysis should really be spelled out. In my opinion it is not enough to state that it was done according to somebody else's recommendations but the power, alpha, effect size, etc that was used for calculation should be provided.
• Were participants aware of the number of trials or any potential distribution within them? I'm asking because a participant might think that CW and CCW spinning figures are distributed in a certain way and adjust their responses accordingly.
• 2 linked limitations of the presented study are that the authors did not obfuscate one eye at a time or provide eye tracking measures. Those the authors cannot truely know whether or not the participants were actually focussing on the fixation cross or not.
• The authors report that most people show a bias towards right handed silouhettes but that implies that some people don't and also that individuals may change their bias over time. This means that this bias is inherently malleable. The authors also report that there may be an (evolutionary) advantage to this bias. Now I wonder if people can train themselves to get a competative advantage (e.g. if faced against a player in a tennis match of certain handedness or with a certain play pattern) or changes occur either under stress or pressure. Stress as a performance modulater has been discussed for a long time but for example recently non-invasive brain stimulation tools have become ever more popular even in sports or trianing settings (e.g. Friehs et al 2020, Electrify your Game, JoCognEnhancement; Friehs et al., 2021, Shocking Advantage, IntJoHumCompStudies; Ruf et al., 2017, Augmentation of WM training by tDCS, ScientificReports; Martin et al., 2014, use of tDCS to enhance cognitive training, Experimental Brain Research). Maybe the authors could speculate on this

Author Response

Point 1: The authors state in their abstract and other times in the manuscript that the indication of the spinning rotation (CW or CCW) indirectly also is linked to perceived handedness. Although I'd be inclined to believe the authors here, they did not ask participants for the perceived handedness and authors should be careful with statements like this.


Response 1: We thank the Reviewer for addressing this point. We have mentioned this limitation in the last paragraph of the revised Discussion.

Point 2: The power analysis should really be spelled out. In my opinion it is not enough to state that it was done according to somebody else's recommendations but the power, alpha, effect size, etc that was used for calculation should be provided.

Response 2: We thank the Reviewer for her/his suggestion, and we have now included this information in Table 1 of the revised manuscript.

Point 3: Were participants aware of the number of trials or any potential distribution within them? I'm asking because a participant might think that CW and CCW spinning figures are distributed in a certain way and adjust their responses accordingly.

Response 3: We did not provide to participants any information about the number of trials or the potential distribution of CW and CCW stimuli (on the other hand, any statement on the latter issue could be misleading because the proportion of CW and CCW rotations depends on participants’ perceptual interpretation). We have not included any change in the manuscript in this regard, but we are available to modify the text if requested.

Point 4: 2 linked limitations of the presented study are that the authors did not obfuscate one eye at a time or provide eye tracking measures. Those the authors cannot truly know whether or not the participants were actually focussing on the fixation cross or not.

Response 4: We thank the Reviewer for stressing this point, and we have addressed it in the last paragraph of the revised Discussion.

Point 5: The authors report that most people show a bias towards right-handed silhouettes but that implies that some people don't and also that individuals may change their bias over time. This means that this bias is inherently malleable. The authors also report that there may be an (evolutionary) advantage to this bias. Now I wonder if people can train themselves to get a competitive advantage (e.g. if faced against a player in a tennis match of certain handedness or with a certain play pattern) or changes occur either under stress or pressure. Stress as a performance modulator has been discussed for a long time but for example recently non-invasive brain stimulation tools have become ever more popular even in sports or training settings (e.g. Friehs et al 2020, Electrify your Game, JoCognEnhancement; Friehs et al., 2021, Shocking Advantage, IntJoHumCompStudies; Ruf et al., 2017, Augmentation of WM training by tDCS, ScientificReports; Martin et al., 2014, use of tDCS to enhance cognitive training, Experimental Brain Research). Maybe the authors could speculate on this.


Response 5: We thank the Reviewer for her/his suggestion. We have now included the suggested references (along with a few on the effect of stress) in the fourth paragraph of the Discussion section.