Psychosis proneness, loneliness, and hallucinations in nonclinical individuals

Sarah Hope Lincoln; Taylor Johnson; Sarah Kim; Emma Edenbaum; Jill M. Hooley

doi:10.1371/journal.pone.0251753

Peer Review History

Original SubmissionDecember 13, 2020
4 Mar 2021 Decision Letter - Thomas M. Olino, Editor PONE-D-20-39171 Psychosis Proneness, Loneliness, and Hallucinations in Nonclinical Individuals PLOS ONE Dear Dr. Lincoln, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. I was fortunate to receive reviews from two experts in this area. I thank them for their attention to this manuscript. The reviewers identify that there are important contributions of the work. However, they also note some areas of the manuscript that could be clearer in presentation. Some of these may lead to additional presentation of analyses for clarity. These may best be accomplished through inclusion of bivariate correlations among study variables. Reviewers note that some questions about the inclusion/testing of mediation (rather than moderation); I think that it is also critical to refrain from language of mediation in light of the cross-sectional design. Reviewer 1 also noted areas of the conceptual foundation of the work that could be elaborated on in the introduction. Beyond the issues noted by the Reviewers, I also wanted to highlight a need to describe magnitude of effects reported by previous studies using the White Christmas paradigm. The corresponding need is to qualify findings in light of the study’s ability to recover those effects. I am not asking for a post-hoc power analysis based on this study’s finding, but to identify the minimum effect that could have been found given the study design. Conversely, as the conclusions are written in a way that is “supporting the null hypothesis,” recent methods have been developed to show that associations are smaller than what would be a meaningful effect, such as using equivalence testing (e.g., Lakens, Scheek, & Isager, 2018; https://doi.org/10.1177/2515245918770963). Please submit your revised manuscript by Apr 18 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. 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Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. 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(Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: Manuscript Number: PONE-D-20-39171 Title: Psychosis Proneness, Loneliness, and Hallucinations in Nonclinical Individuals Introduction This is an interesting manuscript on the relationships between psychosis proneness, loneliness, and auditory hallucinations in a nonclinical sample using an adaptation of the well-validated paradigm, White Christmas. The authors provide sound justification for investigating this question. In terms of findings, while the authors found that over half the sample reported at least one hallucination experience in response to the task, no correlations were observed between the number of hallucinations, schizotypy, and propensity to hallucinate. While the study is overall clearly written, further clarification regarding the statistical analyses are needed, particularly whether mediation was used. For example, the authors describe the aim of investigating whether loneliness mediated relationships, but it is unclear what types of mediation analyses were employed, if any. Overall, this manuscript is well-constructed and offers contributions to the field in this area. Please see major and minor issues noted below. Major Issues It would be useful to have a more in depth description of nonclinical psychosis and schizotypy earlier on for readers that may not be as familiar with experiences endorsed by this group. The authors might consider discussing, in the limitations section perhaps, that the correlational approach to the study does not necessarily get at mechanism, but instead hints towards processes involved. The authors discuss unknown mechanistic understanding of these processes in the introduction and clarification that the analyses employed are not directly examining mechanism can more accurately help with interpreting correlational findings. How did the authors consider and account for site differences between the two universities? Did you conduct any analyses to support combining the samples? The authors might consider adding in statistical analyses to support the written phrase, “This song was better known to students in our pilot testing” described in the methods section. The authors discuss statistical analyses generally, but it appears there is not a data analysis section describing which tests were employed. For example, the authors discuss examining mediation in the sample, but it is unclear how this was examined statistically (“we hypothesized that loneliness would mediate the relationship between the number of hallucinations and psychosis-proneness” pg. 5). Did the authors use mediation statistics? Along these lines, what type of log transformation did the authors use? The inclusion of the limitation of utilizing a purely undergraduate sample should be discussed briefly. Minor Issues There are minor spelling and grammar mistakes throughout (e.g. pg. 4, I think you mean current study, also on page 4, a period I missing after the second sentence in the last paragraph, a comma missing in the last paragraph on pg. 3). Furthermore, in some places, the authors write psychotic like and psychotic-like; consistency in this can enhance readability. Reviewer #2: The authors examined relations between loneliness, hallucinations, and schizotpy in a nonclinical sample of undergraduate students. The article is well-written and clear with an appropriate discussion of the null findings in the context of the study’s limitations. There are only few minor suggestions/questions for improvement of the manuscript: 1) Why did the authors hypothesize a mediation rather than a moderation model for the effect of loneliness on psychosis proneness and hallucinations? A justification for this hypothesis is needed. 2) The social desirability measure in the method section comes out of nowhere and there is no explanation for why it is included. It is also never referenced after the method section. The authors should remove this from the manuscript or provide a rationale for its inclusion and relevant findings. 3) The authors may want to discuss adapting the paradigm as a limitation and speculate on whether or not this could have influenced their findings. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0251753.r001
Revision 1
29 Apr 2021 Author Response April 26, 2021 RE: PONE-D-20-39171 Dear Dr. Olino, Thank you for your careful review and constructive comments provided on our manuscript “Psychosis Proneness, Loneliness, and Hallucinations in Nonclinical Individuals.” To further strengthen our submission, we have addressed each of the additional concerns raised, and we believe the review process has improved the overall quality of our submission. Additionally, we have looked at equivalence testing for this paper and have documented those results in response to your feedback below. We welcome any further discussion or questions of that method; it was new to us and interesting to learn about. Thank you for your time and efforts in considering our revised manuscript. Comment from Editor Beyond the issues noted by the Reviewers, I also wanted to highlight a need to describe magnitude of effects reported by previous studies using the White Christmas paradigm. The corresponding need is to qualify findings in light of the study’s ability to recover those effects. I am not asking for a post-hoc power analysis based on this study’s finding, but to identify the minimum effect that could have been found given the study design. Conversely, as the conclusions are written in a way that is “supporting the null hypothesis,” recent methods have been developed to show that associations are smaller than what would be a meaningful effect, such as using equivalence testing (e.g., Lakens, Scheek, & Isager, 2018; https://doi.org/10.1177/2515245918770963). Thank you for this comment. We have gone back and calculated the effect sizes from previous papers, specifically van de Ven & Merckelbach (2003) and Merckelbach & van de Ven (2001). In Merckelbach & van de Ven (2001), 32 % of the people reported a hallucination, and they found a significant difference between those who heard the hallucinations and those who did not on the Launay-Slade Hallucination Scale with a moderate effect size (d = 0.62). In van de Ven & Merckelbach (2003) they did not find a difference between groups on either the Schizotypal Personality Scale (d = .25) or the Launay-Slade Hallucination Scale (d = .41). In looking at our data, with our sample size, we have 76% power to detect a moderate effect size, but only 20% power to detect a smaller effect. In the article you reference (Lakens et al., 2018) they talk about picking the Smallest Effect Size of Interest (SESOI); they suggest starting with the “largest effect size that, when observed in the original study, would not have been statistically significant.” In this instance, the effect size d = .41 is the largest non-significant effect size. In using the Two One Sided T-tests (TOST) for correlations we find that our confidence interval does fall within the upper and lower bounds and thus is not significantly different from zero (Figure 1). At the same time, given that we would want the White Christmas paradigm to potentially be an indicator of a vulnerability to psychosis, we would likely want a larger effect in order for it to be clinically meaningful. Because we had previously not been familiar with equivalence testing, we have not included these results in our manuscript, but in deference to your comment we have stated in the discussion Though we failed to find evidence of an association that does not mean that no association exists. Figure 1. Number of hallucinations correlated with schizotypy score. Our confidence interval falls within the equivalence bounds. Reviewer #1 1. It would be useful to have a more in depth description of nonclinical psychosis and schizotypy earlier on for readers that may not be as familiar with experiences endorsed by this group. Thank you for this suggestion. We have now included a paragraph about schizotypy in the introduction to hopefully make this construct clearer to readers. Schizotypy is a personality dimension that indicates a propensity to develop schizophrenia, and may reflect a psychosis phenotype (Van Os, Linscott, Myin-Germeys, Delespaul, & Krabbendam, 2009). Schizotypy has three dimensional factors which correspond with the positive, negative, and disorganized symptoms in schizophrenia (Nelson, Seal, Pantelis, & Phillips, 2013). Schizotypal characteristics include magical thinking, paranoia, unusual perceptual experiences, odd beliefs and behavior, disorganized speech, and social anhedonia. Schizophrenia spectrum disorders and schizotypy share commonalities across neuropsychological, social and environmental, and biological factors (Neal et al., 2013). 2. The authors might consider discussing, in the limitations section perhaps, that the correlational approach to the study does not necessarily get at mechanism, but instead hints towards processes involved. The authors discuss unknown mechanistic understanding of these processes in the introduction and clarification that the analyses employed are not directly examining mechanism can more accurately help with interpreting correlational findings. Thank you for this suggestion; you’re right, we do not look at mechanisms. We have added in the discussion the following sentences: An additional limitation is that the correlational nature of this study did not allow us to look at the mechanism by which the phenomenon may be occurring. Our analyses do not directly assess the mechanism. 3. How did the authors consider and account for site differences between the two universities? Did you conduct any analyses to support combining the samples? Thank you for this suggestion. We have run tests comparing the two groups. There is no difference for age (p = .061), schizotypy total scores (p = .447), loneliness (p = .844), and propensity to hallucinate (p = .168). Nor was there a difference on the number of people who heard hallucinations through the white noise (p = .644). 4. The authors might consider adding in statistical analyses to support the written phrase, “This song was better known to students in our pilot testing” described in the methods section. Thank you for this suggestion. We piloted the study with the undergraduate students in our lab at the time (n ~ 8), but unfortunately we did not collect data on these individuals. 5. The authors discuss statistical analyses generally, but it appears there is not a data analysis section describing which tests were employed. For example, the authors discuss examining mediation in the sample, but it is unclear how this was examined statistically (“we hypothesized that loneliness would mediate the relationship between the number of hallucinations and psychosis-proneness” pg. 5). Did the authors use mediation statistics? Along these lines, what type of log transformation did the authors use? Thank you for this comment. We have now added a data analysis section that reads: For this study we will first conduct correlation analyses assessing the relationships between number of hallucinations and both schizotypy and propensity to hallucinate. If a significant relationship is found between either the number of hallucinations and schizotypy or the number of hallucinations and propensity to hallucinate, we will conduct mediation analyses, testing loneliness as the mediator between these variables. We have further clarified that mediation analyses were not conducted, because we did not observe a statistically significant relationship between number of hallucinations and either schizotypy or propensity to hallucinate. There was no relationship to mediate. Additionally, we used a log10 for our log transformation, we have included this information in the results section, but not in the data analysis plan, as we did not a priori plan to do log transformations. 6. The inclusion of the limitation of utilizing a purely undergraduate sample should be discussed briefly. Thank you for this suggestion. We have added the following sentence to the discussion section. We may also be limited by examining these phenomenon in a college student sample. 7. There are minor spelling and grammar mistakes throughout (e.g. pg. 4, I think you mean current study, also on page 4, a period I missing after the second sentence in the last paragraph, a comma missing in the last paragraph on pg. 3). Furthermore, in some places, the authors write psychotic like and psychotic-like; consistency in this can enhance readability. Thank you for these notes. We have gone through a proofread the paper to correct for any grammatical errors and we have changed “psychotic like” to “psychotic-like” throughout the paper. Reviewer #2 8. Why did the authors hypothesize a mediation rather than a moderation model for the effect of loneliness on psychosis proneness and hallucinations? A justification for this hypothesis is needed. Thank you for this comment. We hypothesized a mediation because we thought that loneliness would explain the relationship between the two variables rather than have an effect on its strength or direction. This idea is based off of the social deafferentation hypothesis which suggests that lack of social input may lead to psychotic symptoms like hallucinations. We thought that loneliness, as a proxy for lack of social input, would explain why there was a relationship between hearing music through the white noise and the schizotypy scores. We did not end up running mediation analyses because we did not see a significant relationship between hallucinations and either schizotypy scores or the revised hallucination scale; thus there was no relationship to mediate. 9. The social desirability measure in the method section comes out of nowhere and there is no explanation for why it is included. It is also never referenced after the method section. The authors should remove this from the manuscript or provide a rationale for its inclusion and relevant findings. Thank you for pointing this out. We have removed reference to the social desirability scale as we did not use this in our reported analyses. 10. The authors may want to discuss adapting the paradigm as a limitation and speculate on whether or not this could have influenced their findings. Thank you for this suggestion. We have added the following sentences to our discussion section. We should note that we modified the original paradigm in two ways. First, we did not use the song White Christmas. Second, white noise can vary a great deal in its frequencies and intensities; we do not know what white noise was used in the original paradigms and it is possible their white noise differs from the white noise we used. However, we do not think these two modifications have an effect on our data, as we see approximately the same percentage of individuals reporting hallucinations in the white noise as with previous studies. Again, thank you for your careful review and consideration of our manuscript. We truly believe the Reviewers’ suggestions have contributed to an improved product. Sincerely, Sarah Hope Lincoln, Ph.D. https://doi.org/10.1371/journal.pone.0251753.r002
3 May 2021 Decision Letter - Thomas M. Olino, Editor Psychosis Proneness, Loneliness, and Hallucinations in Nonclinical Individuals PONE-D-20-39171R1 Dear Dr. Lincoln, I reviewed your responses and revision and saw that you were fully responsive to the previous comments. I do not see a need to have the manuscript sent out for an additional review. We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Thomas M. Olino Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0251753.r003
Formally Accepted
20 May 2021 Acceptance Letter - Thomas M. Olino, Editor PONE-D-20-39171R1 Psychosis Proneness, Loneliness, and Hallucinations in Nonclinical Individuals Dear Dr. Lincoln: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Thomas M. Olino Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0251753.r004

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