What the best diet is has always been an area of contention. But one thing is clear: Meat is not necessary for health or fitness, and a diet high in plant proteins may well be especially healthy (e.g. Herpich et al., 2022). Further, plant- rather than animal-based diets leave a lower carbon footprint. So what might hold people back from adopting a plant-based diet? One reason is that people may understandably approach their doctor for advice; and the doctor may advise against it, given that many doctors are not well trained in nutrition (Crowley et al., 2019).

Espinosa et al. (2022) conducted a randomised control trial on French general practitioners with 200 doctors given a leaflet and access to an online platform, and 200 controls. The information in the materials concerned the health benefits of plant-based diets, and what nutrients (e.g. B12) may be deficient and what may not be. Attitudes towards and knowledge about plant-based diets was assessed. On a scale of 0-100% expressing whether they would advise for or against (0 = not at all, 100 = absolutely), the intervention shifted attitudes making them more positive about plant based diets by 17 percentage points. However, knowledge of specifically what is worth testing for (e.g. is zinc deficiency more probable or not?) did not change much. The research shows just what can be achieved by a small leaflet (shifting attitudes) and what may require more extensive training (knowledge of relevant medical practice).

The Stage 2 manuscript was evaluated over one round of in-depth review. Based on the responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 2 criteria and awarded a positive recommendation.
 
URL to the preregistered Stage 1 protocol: https://osf.io/fc9gp
 
Level of bias control achieved: Level 6. No part of the data or evidence that was used to answer the research question existed prior to Stage 1 in-principle acceptance.
 
List of eligible PCI RR-friendly journals:

 

1. Crowley, J., Ball, L. & Hiddink, G. J. (2019.) Nutrition in medical education: a systematic review. Lancet Planetary Health. 3, e379–e389. https://doi.org/10.1016/S2542-5196(19)30171-8

 

2. Herpich, C., Müller-Werdan, U., & Norman, K. (2022). Role of plant-based diets in promoting health and longevity. Maturitas, 165, 47-51. https://doi.org/10.1016/j.maturitas.2022.07.003

 

3. Espinosa, R., Arpinon, T., Maginot, P., Demange, S. & Peureux, F. (2022). Removing barriers to plant-based diets: assisting doctors with vegan patients, acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/kq6eh?view_only=66eab29c7acb4aebbcec4631cbcb9217

Social cognition involves complex processes including empathy, mentalizing, and compassion, which rely on structural connectivity and specifically white matter (WM) integrity. Prior research suggests that deficits in social cognition are linked to deficient structural connectivity, indicating that the latter might be an essential foundation for social cognitive abilities. In the current study, Hansl et al. (2025) explore the relationship between social cognition and white matter (WM) integrity in the brain across different populations, by means of a systematic review and meta-analyses. Using diffusion-weighted imaging data, the authors aim to identify specific WM tracts most associated with social cognition. Meta-analyses of region-of-interest (ROI)-based studies will provide further insights, while meta-regression and subgroup analyses will examine differences across social cognitive constructs, imaging metrics, clinical conditions, and age groups. The findings could clarify global and specific WM contributions to social cognition, guiding future research on brain structure-function relationships in social cognition across various populations.

 

The Stage 1 submission was evaluated by two expert reviewers. After two rounds of revision, the recommender judged that the manuscript met the Stage 1 criteria and awarded in-principle acceptance (IPA).

 

URL to the preregistered Stage 1 protocol: https://osf.io/6n3jy (under temporary private embargo)

 

Level of bias control achieved: Level 2. At least some data/evidence that will be used to answer the research question has been accessed and partially observed by the authors, but the authors certify that they have not yet observed the key variables within the data that will be used to answer the research question and they have taken additional steps to maximise bias control and rigour.

 
List of eligible PCI RR-friendly journals:
 

 

 

1. Hansl, R., Maliske, L. Z., Valk, S. L., & Kanske, P. (2025). Social cognition as a matter of structural brain connections? A systematic review and diffusion weighted imaging meta-analysis. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/6n3jy

Both research and public debates around social media use tend to involve a premise of positivity bias, which refers to presenting one’s life in an overly positive light by various different means. This premise contributes to multiple potentially important follow-up hypotheses, such as the fear of missing out and low self-image effects, due to repeated consumption of positive social media content (e.g., Bayer et al. 2020, for a review). The positivity bias of social media use, itself, has received limited research attention. 
 
In the present study, Masciantonio and colleagues (2025) tested positivity bias in the context of three social media platforms: Facebook, Instagram, and X. The experiment involved recruiting participants (n=312) into platform-specific user groups and crafting posts to be shared with friends as well as respective social media audiences. For social media positivity bias to differ from everyday positivity bias, posts in the former should introduce more positive valence in comparison to offline sharing—and if the platforms differ in their encouragement of positivity bias, they should introduce significant between-platform differences in valence.
 
Based on how the participants reported events, the study found no significant differences between everyday and social media positivity bias, but messages posted on Twitter/X had a more negative valence than posts in other social media platforms. The results would be consistent with the implication that people's positive actions in social media simply follow the natural human tendency to present oneself positively to others—a hypothesis that should be investigated in follow-up work. More research attention should also be given to specific design features, which may contribute to platform-specific differences in user habits, as suggested by the distinct valence rate found in relation to Twitter/X.

 

The Stage 2 manuscript was evaluated by three experts (areas: experimental methods, social media, statistics) via in-depth peer review across two rounds, with one reviewer returning to validate analysis code and methdological accuracy on a final round. Based on the authors’ careful responses and revisions, the revised manuscript was judged to meet the Stage 2 criteria and was awarded a positive recommendation. 

 
URL to the preregistered Stage 1 protocol: https://osf.io/9z6hm
 
Level of bias control achieved: Level 6. No part of the data or evidence that was used to answer the research question was generated until after IPA.  
 
List of eligible PCI RR-friendly journals:

 

 

 
1. Bayer, J. B., Triệu, P., & Ellison, N. B. (2020). Social media elements, ecologies, and effects. Annual review of psychology, 71, 471-497. https:// doi.org/10.1146/annurev-psych-010419-050944

 

2. Masciantonio, A., Heiser, N., & Cherbonnier, A. (2025). Unveiling the Positivity Bias on Social Media: A Registered Experimental Study On Facebook, Instagram, And X [Stage 2]. Acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/s93yu 

The Spatial-Numerical Association of Response Codes (SNARC) effect (Dehaene et al., 1993) is a key phenomenon in numerical cognition. It describes the tendency for individuals to respond faster to smaller numbers with a left-side key and to larger numbers with a right-side key, suggesting a mental mapping of numerical magnitudes onto space. While this effect has been widely replicated, its precise nature remains debated, particularly regarding its task dependency.

 

In this Stage 1 Registered Report, Roth et al. (2025) present a highly powered study that systematically investigates whether the SNARC effect differs in two widely used numerical cognition tasks: magnitude classification (MC) and parity judgment (PJ). In the MC task, participants determine whether a presented number is smaller or larger than a reference value (typically 5). This task explicitly requires magnitude processing, making numerical magnitude directly relevant to the response. In contrast, the PJ task requires participants to judge whether a number is odd or even, a decision that does not explicitly involve numerical magnitude.

 

The authors address a fundamental theoretical question in numerical cognition: while the SNARC effect in PJ is often considered continuous, does it follow a categorical pattern in MC? To investigate this, the study directly compares continuous and categorical representations of the SNARC effect across these two tasks, using Bayesian statistical approaches to determine the best-fitting model. By systematically analysing the SNARC effect in these widely used paradigms, this work aims to refine our understanding of how numerical magnitudes are mapped onto space and whether this mapping depends on task demands. The findings of this study will provide crucial insights into the cognitive mechanisms underlying numerical-spatial associations, highlighting the extent to which task structure shapes the emergence of the SNARC effect.

 

Three expert reviewers provided valuable feedback across multiple rounds of review. Based on ​detailed responses to the reviewers’ and recommender’s comments, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance.​​​

 
URL to the preregistered Stage 1 protocol: https://osf.io/968ad

 

Level of bias control achieved: Level 6. No part of the data or evidence that will be used to answer the research question yet exists and no part will be generated until after IPA.
 
List of eligible PCI RR-friendly journals:

 

 

 

1. Dehaene, S., Bossini, S., & Giraux, P. (1993). The mental representation of parity and number magnitude. Journal of Experimental Psychology: General, 122(3), 371–396. https://doi.org/10.1037/0096-3445.122.3.371

 

2. Roth, L., Cipora, K., Overlander, A. T., Nuerk, H.-C., & Reips, U.-D. (2025). Shape of SNARC: How task-dependent are Spatial-Numerical Associations? A highly powered online experiment. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/968ad

The replication crisis/credibility revolution has driven a vast number of changes to our research environment (Korbmacher et al., 2023) including a much needed spotlight on issues surrounding measurement (Flake & Fried, 2020). As general understanding and awareness has increased surrounding the 'garden of forking paths' or 'researcher degrees of freedom' (Simmons et al., 2011), and the various decisions made during the scientific process that could impact the conclusions drawn by the process, so too should our interest in meta-research that tells us more about the methodological processes we follow, and how discretionary decisions may influence the design, analysis and reporting of a project.

 

Peeters et al. (2025) have proposed a systematic literature review of this nature, mapping the methodological variation in experience sampling methods (ESM) from the design stage all the way to dissemination. It starts this journey by mapping how ESM studies vary e.g., in design, considering a variety of factors like sample size, number of measurements, and sampling scheme. It also evaluates reporting quality, rationales provided, and captures the extent of open science practices adopted. Covering many parts of the research process that get assumed, unreported or otherwise unjustified, the proposed work looks set to springboard an important body of work that can tell us more effectively how to design, implement and report ESM studies.

 

The Stage 1 submission was reviewed over one round of in-depth review with two reviewers. Based on detailed responses to reviewers’ feedback, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance.

 

 
Level of bias control achieved: Level 1. At least some of the data/evidence that will be used to the answer the research question has been accessed and observed by the authors, including key variables, but the authors certify that they have not yet performed any of their preregistered analyses, and in addition they have taken stringent steps to reduce the risk of bias.
 
List of eligible PCI-RR-friendly journals:

 

 

1. Flake, J. K., & Fried, E. I. (2020). Measurement schmeasurement: Questionable measurement practices and how to avoid them. Advances in Methods and Practices in Psychological Science, 3, 456-465. https://doi.org/10.1177/2515245920952393

 

2. Korbmacher, M., Azevedo, F., Pennington, C. R., Hartmann, H., Pownall, M., Schmidt, K., ... & Evans, T. (2023). The replication crisis has led to positive structural, procedural, and community changes. Communications Psychology, 1, 3. https://doi.org/10.1038/s44271-023-00003-2

 

3. Peeters, L., Van Den Noortgate, W., Blanchard, M. A., Eisele, G., Kirtley, O., Artner, R., & Lafit, G. (2025). Mapping Methodological Variation in ESM Research from Design to Data Analysis: A Systematic Review. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/ztvn3

 

4. Simmons, J. P., Nelson, L. D., & Simonsohn, U. (2011). False-positive psychology: Undisclosed flexibility in data collection and analysis allows presenting anything as significant. Psychological Science, 22, 1359-1366. https://doi.org/10.1177/0956797611417632