Through the Frosted Glass Pane: Blunted Physiological Responses to Extremely Under- and Over-Sized Body Pictures in Female Adolescents with Obesity—An Experimental Pilot Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript "Blunted physiological responses to extremely under- and over-sized body pictures in female adolescents with obesity: an experimental pilot study" presents a well-executed pilot study combining subjective and physiological assessments of emotional responses to body image cues. The topic is relevant for adolescent obesity research, highlighting neurobiological and motivational mechanisms. The manuscript is generally well-organized but would benefit from several clarifications and focused improvements throughout, as detailed below

Major Issues

1. Abstract Structure and Focus: I should recommend to condense the methods focusing more on the primary findings and clinical implications. State limitations explicitly at the end of the abstract, e.g.:

"Findings suggest diminished physiological salience of body-related cues in obese adolescents, which may undermine intrinsic motivation for weight loss. The limited sample size restricts generalizability."

2. Introduction

Reduce general epidemiological background and focus more sharply on gaps in motivational research. Shorten longer passages, e.g., combine lines 34-40 on weight loss recidivism into a single concise paragraph.

3. Results
4. Clarify in figure legends the sample sizes and summarize main result interpretation.
   1. Revise figure 7 and replace values 1, 2, and 3 on the x-axis with the groups studied (extremely under-sized, normal-sized, extremely over-sized.
   2. Line 446: "Under-sized bodies elicited a significantly higher SCR than normal-sized bodies (p = .032). However, the SCR increase from normal-sized to over-sized bodies did not reach significance..." Recommendation: "Under-sized bodies elicited a significantly higher SCR than normal-sized bodies (p = .032). However, the SCR increase from normal-sized to over-sized bodies did not reach significance..."

 

4. Discussion. A) Clarify the transition between mechanisms. For instance: In Physiological Downregulation section "While habituation could partly explain diminished emotional responses to overweight body images due to regular exposure in daily life, our results also showed reduced reactivity to underweight and normal-sized images. This suggests that other processes, such as neural changes in motivational pathways, may be involved.           B) Summarize limitations in a distinct, concise paragraph: "This study is limited by its small sample size, single-gender population, and lack of binge eating disorder assessment. These factors restrict the generalizability of the findings. Future studies should aim for larger, more diverse samples and include comprehensive psychiatric profiling."

Minor Issues

1. Unify abbreviations in text and tables (e.g., always use SCR, never mix with full spellings).
2. Ensure reference formatting is consistent 

 

Author Response

Major Issues

Abstract

Comments 1: I should recommend to condense the methods focusing more on the primary findings and clinical implications. State limitations explicitly at the end of the abstract, e.g.: "Findings suggest diminished physiological salience of body-related cues in obese adolescents, which may undermine intrinsic motivation for weight loss. The limited sample size restricts generalizability."

Response 1: We agree with this comment. The abstract was revised to reduce methodological detail (by removing the sentence “The Self-Assessment Manikin was used as subjective measure, while startle reflex magnitude and skin conductance response served as objective measures.“) and to place greater emphasis on the primary findings (emotional blunting and subjective vs. objective dissociation, Line 25 ff.) and their potential clinical implications. In addition, limitations are now explicitly stated at the end of the abstract. Specifically, we added the sentence: “The limited sample size restricts generalizability." (Line 28)

Introduction 

Comments 2: Reduce general epidemiological background and focus more sharply on gaps in motivational research. Shorten longer passages, e.g., combine lines 34-40 on weight loss recidivism into a single concise paragraph.

Response 2: We agree with this comment. As a first step, we condensed the epidemiological background by summarizing lines 34–40 to the following shorter passage: “Since the 1970s, the proportion of overweight children and adolescents increased by a factor of eight [5]. During the COVID pandemic, a further increase was observed [6–7]. Approximately 80% of overweight adolescents will remain over-sized into adulthood [8–9]“ (Line 34-38). We also revised the surrounding text to improve the focus on motivational aspects of weight regulation. The following sentence was added: “Previous research has largely relied on self-report measures, whereas experimental studies examining implicit or involuntary motivational processes remain limited, leaving key mechanisms insufficiently understood."(Line 39-41).    

Results

Comments 3: Clarify in figure legends the sample sizes and summarize main result interpretation.

Response 3: Agree. We have accordingly added the sample size and a main result interpretation to all figure legends, e.g. for Figure 1: “Changes in the Self-Assessment Manikin (SAM) valence value for the three standard picture categories (positive, neutral, negative) for both groups (20 patients, 24 controls) ... The figure illustrates a linear decrease of the SAM valence value from positive over neutral to negative pictures.”, Line 313 -316 ).

Comments 3.1: Revise figure 7 and replace values 1, 2, and 3 on the x-axis with the groups studied (extremely under-sized, normal-sized, extremely over-sized.

Response 3.1: Thank you for pointing out this error to us. We have accordingly modified Figure 7.

Comments 3.2: Line 446: "Under-sized bodies elicited a significantly higher SCR than normal-sized bodies (p = .032). However, the SCR increase from normal-sized to over-sized bodies did not reach significance..." Recommendation: "Under-sized bodies elicited a significantly higher SCR than normal-sized bodies (p = .032). However, the SCR increase from normal-sized to over-sized bodies did not reach significance..."

Response 3.2: Thank you for this comment. For consistency with the rest of the manuscript, we slightly adjusted the wording by omitting “statistical” before “significance” (Line 450).

Discussion

Comments 4.1: Clarify the transition between mechanisms. For instance: In Physiological Downregulation section "While habituation could partly explain diminished emotional responses to overweight body images due to regular exposure in daily life, our results also showed reduced reactivity to underweight and normal-sized images. This suggests that other processes, such as neural changes in motivational pathways, may be involved."    

Response 4.1: We agree. A summarizing transition was added at the end of the “Physiological down-regulation” section: “Taken together, while habituation could partly explain diminished emotional responses to overweight body images due to regular exposure in daily life, our results also showed reduced reactivity to underweight and normal-sized images. This pattern suggests that additional processes, such as body-cue-related avoidance behavior and neural changes in motivational pathways, may be involved.” (Line 667 – 680)

Comments 4.2: Summarize limitations in a distinct, concise paragraph: "This study is limited by its small sample size, single-gender population, and lack of binge eating disorder assessment. These factors restrict the generalizability of the findings. Future studies should aim for larger, more diverse samples and include comprehensive psychiatric profiling."

Response 4.2: We agree with this comment. The recommended paragraph was added at the end of the limitations section: “Overall, this study is limited by its small sample size, single-gender population, and lack of binge eating disorder assessment. These factors restrict the generalizability of the findings. Future studies should aim for larger, more diverse samples and include comprehensive psychiatric profiling.”  (Line 744 – 746).

Minor Issues

Comments 5: Unify abbreviations in text and tables (e.g., always use SCR, never mix with full spellings).

Response 5: Thank you detecting this mistake. The abbreviations were examined and corrected if necessary, e.g. for the SCR, ANOVA and SAM

Comments 6: Ensure reference formatting is consistent 

Response 6: Thank you for detecting this mistake. The references were checked, and seven corrections were made (Reference Number 17, 33, 42, 46, 48, 55, and 78)

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

I think that this work is an important contribution of international interest in the field of body image perception in the critical adolescent period. Overweight and obesity are among the most important challenges for international health care, and the application of new strategies for assessing physical and mental health is important for preventing the risk of these and for recognizing cases in which intervention is necessary.

The design and the methodologies of the study are appropriate, and the level of English is also satisfactory. The results are interesting and clearly described. The statistical applications are appropriate. The tables are relevant and well described. The discussion is clear and satisfactorily argues the results. The literature is well-referenced and relevant.

Despite the innovative analysis approach, the results are affected by the small sample size. The authors are aware of this limitation and provide extensive explanations throughout the manuscript, clarifying in the title that this is a pilot study. For this reason, I think that this study is suitable for publication in the current version.

Author Response

Comment: I think that this work is an important contribution of international interest in the field of body image perception in the critical adolescent period. Overweight and obesity are among the most important challenges for international health care, and the application of new strategies for assessing physical and mental health is important for preventing the risk of these and for recognizing cases in which intervention is necessary. The design and the methodologies of the study are appropriate, and the level of English is also satisfactory. The results are interesting and clearly described. The statistical applications are appropriate. The tables are relevant and well described. The discussion is clear and satisfactorily argues the results. The literature is well-referenced and relevant. Despite the innovative analysis approach, the results are affected by the small sample size. The authors are aware of this limitation and provide extensive explanations throughout the manuscript, clarifying in the title that this is a pilot study. For this reason, I think that this study is suitable for publication in the current version.

Response: We sincerely thank the reviewer for this positive and thoughtful evaluation and for recognizing the relevance and pilot character of the study.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript "Through the frosted glass pane" applies the starte reflex paradigm to 41 adolescent women to investigate if the physiological response to emotional and body images is aberrant among the obese group. 

Overall, I liked the combination of physiological measures and subjective ratings. My main concern is about the data analysis. Physiological data like SCR (also EMG) is often compared to a baseline. The design allows that. Thre are trials with black images and the startling tone. Thus, I recommend preprocessing the data per individual by finding the nearest "black image", subtract the response and use this difference of baseline vs target as your variable.

Black image with tone at sequence i  - target image (body picture or affective standard picture)

this difference may likely also reduce the skewedness issue(no transformation needed)

From the figures, one can see that the EMG and SCR response is overall larger for body pictures than affective standard pictures (y-axis differ in fig 3 vs 7, and fig 4 vs 8). A formal test of that would be very informative, i.e all respond stronger to body images than the chosen affective images

Minor: please report effect sizes, that also incl the 4 tables in the SOM

effect sizes can be already medium even if p is n.s. given the small N. That is informative as power analysis use effect sizes, not p values.

please plot boxplots, as these allow to see the distribution, median and quartiles.

line 48: do you mean intrinsic motivation?

line 111ff: I would not use the ingress hypothesis 3, but rather state it as it is / write the sentence still under 1.3. but without refering to it as hypothesis 3 as it is not testable

line 245: which percentage of trials had to be set to 0?

line 293f: p-value multiplied? You mean divided? False discovery rate and Bonferroni use stricter p-values, not more lenient

line 300-302: delete - left over from template

line 311ff: please report effect sizes, not just p-values

line 371: shoudl be square (not sqare)

line 420ff: you seem to perform post-hoc tests despite a non-significant interaction effect. This is problematic and needs better justification. It may change if you change the preprocessing steps

line 477 table 2: the ppg vs pcg got misaligned (cg moved down)

line 480 table 3: 8,3 should be 8.3

line 506 table 5 - line numbers are left of the table

line 546 table 6: should be Patients not Patiens

line 547: consider writing "their body" instead "the own body"

line 552 table 7: same as for table 5

line 582 "SCR findings remained stable" - ambiguous formulation since the SCR findings were significant, so you likely mean that there were no changes to the pattern? Or do you mean that SCR was stable as in was not different between the groups and conditions?

line 653 in in body - delete one in

 

Author Response

Major Issues

Comment 1: My main concern is about the data analysis. Physiological data like SCR (also EMG) is often compared to a baseline. The design allows that. There are trials with black images and the startling tone. Thus, I recommend preprocessing the data per individual by finding the nearest "black image", subtract the response and use this difference of baseline vs target as your variable. Black image with tone at sequence i  - target image (body picture or affective standard picture). This difference may likely also reduce the skewedness issue (no transformation needed)

Response 1: We agree that a baseline correction is essential and necessary. However, this baseline correction has already been carried out: A) For the startle reflex, difference values between peak EMG (highest EMG value within 20 to 150 milliseconds after the noise) and baseline EMG (EMG value within the last 100 milliseconds before) were calculated consistent with Blumenthal et al. [59]. A (renewed) correction with the startle reactions during the black screens is an unusual strategy, and only 1/3 of all black screens are provided with a startle, making it difficult to find pairs. B) For the SCR, difference values between peak SCR (highest EDA value within 900 to 4000 milliseconds after image onset) and baseline SCR (EDA value within the last 1000 milliseconds before, representing the last 1000 milliseconds of the preceding black screen) were calculated, according to previous studies*. Extending this time window to the full 12 to 18 seconds of the black screen is problematic, especially since one-third of all black screens are accompanied by startle sounds, which can severely disrupt the baseline determination. In summary, the existing baseline time window is consistent with the guidelines and ensures that disruptions from preceding startle sounds can be avoided. Therefore we recommend using the previous strategy.

Literature references:

Blumenthal, T. D., Cuthbert, B. N., Filion, D. L., Hackley, S., Lipp, O. V., & van Boxtel, A. (2005). Committee report: Guidelines for human startle eyeblink electromyographic studies. Psychophysiology, 42(1), 1–15. https://doi.org/10.1111/j.1469-8986.2005.00271.x

Published studies with a comparable baseline-correction strategy:

Reichel et al. (2013) “Glass fairies” and “bone children”: Adolescents and young adults with anorexia nervosa show positive reactions towards extremely emaciated body pictures measured by the startle reflex paradigm. Psychophysiology, 51 (2), 168–177. doi:10.1111/psyp.12160

Pape et al. (2024). Apples and Oranges: PTSD patients and healthy individuals are not comparable in their subjective and physiological responding to emotion induction and bilateral stimulation. Frontiers in  Psychology, 15. https://doi.org.10.3389/ fpsy g.2 024.1406180

Pape et al. (2023). The riddle of deliberate self-harm: Physiological and subjective effects of self-cutting cues in patients with borderline personality disorder and healthy controls. Personality and mental health, 17(4), 328–351. https://doi.org/10.1002/pmh.1583

Reichel et al.. (2021). Good vibrations: Bilateral tactile stimulation decreases startle magnitude during negative imagination and increases skin conductance response for positive imagination in an affective startle reflex paradigm. European Journal of Trauma & Dissociation, 5(3), 100197. https://doi.org.10.1016/j.ejtd.2020.100197

Comment 2: From the figures, one can see that the EMG and SCR response is overall larger for body pictures than affective standard pictures (y-axis differ in fig 3 vs 7, and fig 4 vs 8). A formal test of that would be very informative, i.e all respond stronger to body images than the chosen affective images

Response 2: Thank you for this important comment. To formally test whether responses differed between body pictures and affective standard pictures, we conducted a two-factorial mixed ANOVA with picture category (body vs. affective standard pictures) as a within-subject factor and group (patients vs. controls) as a between-subject factor. The results are presented in a new subsection (3.3, “Processing of Body Pictures vs. Affective Standard Pictures”, Line 489 - 517) and in a new Supplementary Table S5. Subjective ratings (valence and arousal) showed significant main effects of picture category, while physiological measures demonstrated only partial or non-significant category effects.

Minor Issues

Comment 3:  Please report effect sizes, that also incl the 4 tables in the SOM. Effect sizes can be already medium even if p is n.s. given the small N. That is informative as power analysis use effect sizes, not p values.

Response 3: We agree with this comment. Therefore, we have edited the Results part as well as the Supplementary Material tables: For all main and interaction effects, partial Eta Squares were reported (manuscript: Line 305 ff.; Supplementary Material Tables S1 to S5).

Comment 4: Please plot boxplots, as these allow to see the distribution, median and quartiles.

Response 4: Thank you for this suggestion. We have added boxplots displaying the distribution, median, and quartiles for all relevant measures in the Supplementary Material (Figure S1) to allow detailed inspection of the data distributions. The original figures were retained in the main manuscript to preserve the visualization of condition-related trends.

Comment 5: line 48: do you mean intrinsic motivation?

Response 5: Yes. We have replaced “Internal motivation” by “intrinsic motivation” (Line 46).

Comment 6: line 111ff: I would not use the ingress hypothesis 3, but rather state it as it is / write the sentence still under 1.3. but without referring to it as hypothesis 3 as it is not testable

Response 6: We agree. As the statement is not directly testable, we removed the label “Hypothesis 3” and retained the sentence as a descriptive statement in section 1.3 (Line 109 – 110)

Comment 7: line 245: which percentage of trials had to be set to 0?

Response 7: Approximately 15 % percentage of trials had to be set to 0. We have added this clarification into the text. (Line 254)

Comment 8: line 293f: p-value multiplied? You mean divided? False discovery rate and Bonferroni use stricter p-values, not more lenient

Response 8: Thank you for pointing this out. The wording was corrected by replacing “multiplied” with “divided” (Line 291).

Comment 9: line 300-302: delete - left over from template

Response 9: Thank you for pointing this out. The passage was deleted (Line 296 - 297).

Comment 10:  line 311ff: please report effect sizes, not just p-values

Response 10: Please see our answer to Comment 3.

Comment 11: line 371: should be square (not sqare) 

Response 11: Thank you for pointing this out. The spelling error was corrected (line 464).

Comment 12: line 420ff: you seem to perform post-hoc tests despite a non-significant interaction effect. This is problematic and needs better justification. It may change if you change the preprocessing steps

Response 12: We agree with this concern. Given the non-significant interaction effect, the subsequent analyses were reclassified as exploratory (Line 426). The manuscript was revised accordingly, including the addition of a clarifying sentence emphasizing that the observed differential effects are preliminary and require replication in larger samples (Line 433 - 435): “However, given the non-significant interaction effect, we emphasize that the observed differential effects are preliminary and require replication in larger samples.”

Comment 13: line 477 table 2: the ppg vs pcg got misaligned (cg moved down)

Response 13: Thank you for pointing this out. The spelling error was corrected.

Comment 14: line 480 table 3: 8,3 should be 8.3

Response 14: Thank you for pointing this out. The typing error was corrected.

Comment 15: line 506 table 5 - line numbers are left of the table.

Response 15: Thank you for pointing this out. The line numbers were inadvertently displayed next to Table 5 and have now been removed.

Comment 16: line 546 table 6: should be Patients not Patiens

Response 16: Thank you for pointing this out. The spelling error was corrected.

Comment 17: line 547: consider writing "their body" instead "the own body"

Response 17: Thank you for pointing this out. The term was corrected (Line 567)

 

Comment 18: line 552 table 7: same as for table 5

Response 18: Thank you for pointing this out. The line numbers adjacent to Table 7 have been removed.

Comment 19: line 582 "SCR findings remained stable" - ambiguous formulation since the SCR findings were significant, so you likely mean that there were no changes to the pattern? Or do you mean that SCR was stable as in was not different between the groups and conditions?

Response 19: Thank you for pointing this out. We clarified this passage to indicate that the pattern and significance of the SCR effects remained unchanged after inclusion of the BID-CA score [32], the IEG score [54], and the Contour Drawing Rating Scale score (Thompson and Gray, 1995) as covariates, “compared to the analyses without covariates” (Legend Table 8 and 9)

Comment 20: line 653 in in body - delete one in

Response 20: Thank you for pointing this out. The duplicate word was removed.

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