A behavioral measure of individual differences in schizotypal traits

No more questions nor suggestions. I am happy with this preregistration.

Thank you for the opportunity to review the Stage 1 Registered Report "Stochastic resonance and internal noise in schizotypal traits: a random dot kinematograms paradigm". The research project provides a comprehensive and well-structured exploration of the relationship between Random Dot Kinematogram (RDK) performance and schizotypy traits. The research design, data collection, and analysis methods are rigorous and align with current best practices

Strengths of the Study

Clear Objectives: The study sets clear and relevant research questions that contribute to a deeper understanding of perceptual processing in individuals with varying levels of schizotypy.
Methodological Rigor: The experimental design, is appropriate for the research objectives and measures employed to assess schizotypy are validated and reliable, ensuring the robustness of the findings.
Comprehensive Data Analysis: The statistical techniques used and power estimation are suitable for examining the relationship between schizotypy and task performance. The study effectively handles potential confounding factors and provides a thorough interpretation of the results.
Theoretical Contribution: By linking schizotypy to perceptual differences, the study adds valuable insights to the literature on subclinical psychotic traits.

Suggestions for Further Exploration
Although the study meets high standards, it could benefit from future research directions. For instance, applying a Bayesian Component Analysis (BCA) approach might provide a deeper understanding of the latent structures underlying the perceptual differences observed.

Overall, the research project is a valuable contribution to the field.

I enjoyed reading the introduction and methods, it is a very interesting research agenda. I look forward to read the results! Nonetheless I have some comments that I hope will help the authors to clarify and improve their manuscript.

In general, my main concern is with respect the using of PCA instead of the subscales as main analysis. I also think the hypothesis and its link with the analysis need some clarification. I did not see an adecuate matching between statistical analysis and hypothesis. More details above.

Also, I have other minor comments. Starting with a too big abstract, you may want to consider make it shorter.

INTRODUCTION

Third paragraph add a reference for definition of schizotypy: “Schizotypy refers to a continuum of traits associated with, but less severe than, schizophrenia.”

In the fourth paragraph. You mentioned there is no direct evidence on internal noise in schizotypy. Maybe it would be interesting to describe why using O-LIFE and schizotypy instead of another personality (e.g., any Big-5). Perhaps other personality traits may help better. Which subscale of schizotypy has more internal noise? Also, O-LIFE measure schizotypy as personality does not assumes risk of schizophrenia, as other schizotypy questionnaires do. If you want a model or tendency of psychosis, perhaps other schizotypy questionnaire.

Fifth paragraph in section “Internal Noise in the schizotypal population” contains “a spectrum of traits related to schizophrenia.” This may not be needed because you described the relationship between schizotypy and schizophrenia in previous paragraphs.

Pag 8 second paragraph, you are using “aperiodic slope” but for someone outside the field, it may not be clear what is this. Also, provide a summary of what is the evidence suggesting is there a difference in the slopes or not.

Given you are not using EEG or neuroimaging, maybe you can summarize the electrophysiology and neuroimaging into some brief paragraphs. The intro may be long.

METHODS

Add in methods whether if the number of dots for each trial (both presentations: motion and random) will be the same. My guess is yes, but explicitly specify it.

What is the effect size similar to “effects found for age in Di Ponzio et al. (2024)“?

You are mentioning twice the “one-up, two-down staircase procedure”, in “Manipulated variables” and “Procedure”. I wonder if this is a bit redundant. Perhaps this two sections are needed for the PCI registered reports. Same comment for the subsection “Constant Stimuli Block” it seems that you have explained this already in procedures.

In the section “Measured variables” subsection “Thresholding block” you also describe the one-up two-down method and the “correctly in 70.7%  of  trials”. This is redundant, you are describing this 3 times.

In the section “Planned statistical analyses”, why using O-LIFE PCA as your main analysis, and using the already validated subscales: unusual experiences, cognitive disorganization, and introvertive anhedonia as exploratory analysis? I am not sure why you decided to use PCA, why you want to “capture the underlying dimensions of schizotypal traits” if these are already captured in the questionnaire subscales? This part needs a bit more justification.

With respect the 4th degree polynomial models. What happened if the model assumptions are not met?

In the exploratory analysis, are you planning median split based on the total score of the OLIFE?

Good exclusion criteria, well justified and clear.

The first figure shows high and low schizotypy, this is only for visualization purpose, right? Because I though the high and low was only for exploratory purposes. Perhaps this needs to be specified. Also, I though the main analysis would be conducted with PCA. I am confused.

Why “Hypothesis 2” use Unusual Perceptual Experience. Hypothesis 2 is the same as exploratory analysis? Clarify please.

Given the previous results with Age, are you planning to control by age? It would be nice to have that given you already know this effects.

This seems like an interesting experiment investigating the relative contribution of internal vs external noise in perceptual inference in schizotypy. There are already a few studies out there investigating the contribution of noise in perceptual inference and psychosis-like experience (Haarsma et al., 2023; Benrimoh et al., 2023), limiting its novelty. However, the approach seems solid and could provide further evidence for altered mechanisms in psychosis-like conditions. I would encourage the researchers to ensure that the selection criteria do not undersample individuals with high schizotypy, which might limit hte chance of finding effects. Further, the sample size seems to be on the low side for finding correlations in online samples, which more commonly recruit multiple hundreds of subjects. The limitation to a single questionnaire could provide issues. Including some questionnaires tapping into general anxiety or other psychopathological continuums might proof beneficial in controlling for other parts of schizotypy. Further, other questionnares like the PDI and CAPS could help finding symptom specific correlations in the sample.