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

This study by Diaz-Fong et al. (2025) plans to investigate body dysmorphic disorder (BDD), an understudied psychiatric condition marked by distortions in the perception of a patients’ physical appearance. The authors build on evidence that perceptual symptoms in BDD are underpinned by attentional biases, which may relate to abnormal visual processing and neural connectivity in the dorsal visual stream (DVS; reduced activation) and the ventral visual stream (VVS; increased activation). Prior evidence suggests that activation in the DVS and the VVS may be modifiable by both non-invasive neuromodulation (including transcranial magnetic stimulation), as well as behavioural interventions such as the Visual Modification (ModV) paradigm, which has been suggested to reduce patients’ foveal attention to perceived bodily defects. The ModV paradigm has been specifically linked with altered VVS and DVS activation and connectivity. 

 

Here the authors will test in a within-subject crossover design (N = 40) whether neural connectivity and visual perceptual biases in BDD and subclinical BDD can be modified by combining the effects of altered visual attention in the ModV paradigm with repetitive transcranial magnetic stimulation (continuous and intermittent theta burst stimulation; cTBS and iTBS). By combining a behavioural and an exogenous intervention, the authors predict an increase in the magnitude of clinically meaningful improvements in attentional biases in BDD, with iTBS expected to enhance, and cTBS expected to inhibit the effects of visual attention modification through ModV on neural connectivity (measured using fMRI) and visual processing. More specifically, the effect of TBS is hypothesised to be stronger after patients perform ModV.

 

The Stage 1 manuscript was evaluated by two experts who performed in-depth peer review across multiple rounds of revisions. The authors were responsive in editing their manuscript based on the reviewers’ comments and dedicated much effort to increasing the clarity and interpretability of their power analyses. The revised manuscript was judged to meet the Stage 1 criteria and was awarded in-principle acceptance (IPA). 

URL to the preregistered Stage 1 protocol: https://osf.io/ks425 (under temporary private embargo)
 
Level of bias control achieved: Level 3. At least some data/evidence that will be used to the answer the research question has been previously accessed by the authors (e.g. downloaded or otherwise received), but the authors certify that they have not yet observed any part of the data/evidence.
 
List of eligible PCI RR-friendly journals:

 

 

 

Diaz-Fong, J. P., Lewis, M., Qian, J., Wong, W.-W., Leuchter, A. F., Tadayonnejad, R., Voineskos, D., Konstantinou, G., Lam, E., Blumberger, D. M., Feusner, J. D. (2025). Noninvasive neuromodulation of visual perception and neural connectivity in body dysmorphic disorder: a registered report. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/ks425

It is increasingly recognised that resolving the climate crisis will require not only the reform of law and government policy but collective grassroots action to change individual behaviour and put public pressure on political leaders, companies and institutions to cut emissions. The capacity, however, for individual citizens to take such steps is limited by lack of knowledge/awareness of means and opportunities as well as psychological barriers that can make such actions seem impossible, fruitless or against the person's immediate self-interest. Interventions designed to overcome these obstacles and promote individual behaviour change have met with only limited success, with many based on weak psychological evidence and the outcome measures used to evaluate their success prone to error and bias.

 

In the current submission, Castiglione et al. (2024) propose a series of five studies to test, evaluate, and optimise a longitudinal intervention for engaging young adults (aged 18-35) in individual and collective climate action. Building on existing theory and evidence, the authors have designed an intensive 6-week educational intervention that draws on 12 psychological factors linked to pro-environmental behaviour, including emotional engagement, self-efficacy, collective efficacy, theory of change, cognitive alternatives, perceived behavioral control, implementation intentions, social norms, self-identity, collective identity, appraisal, and faith in institutions. Through the use of ecological momentary assessment (EMA), they plan to measure these targeted psychological correlates as well as individual and collective climate engagement of participants before and after the intervention (and in active groups vs. controls), and then again after a further three months.

 

The current submission is novel in being the first at PCI RR (and possibly the first RR anywhere) to propose an incremental programmatic workflow that combines two innovations: a single Stage 1 protocol leading to multiple Stage 2 outputs (under the PCI RR programmatic track) and a prespecification in which the design of the intervention in later studies is (for now) determined only broadly, with specific parameters to be shaped by the results of the first set of studies (under the PCI RR incremental registrations policy). This particular Stage 1 manuscript specifies the design of study 1 in two samples (high-school and university students in Italy; producing one Stage 2 output for each sample) and the general design of subsequent studies. The details of this later research in study 2 (in the same two populations) and study 3 (university students in the Netherlands) will be developed sequentially based on the results of the previous Stage 2 outputs and the state of the literature at that time.

 

The Stage 1 manuscript was evaluated over two rounds of in-depth review. Based on detailed responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance (IPA). Following the completion of study 1, the authors will submit an updated Stage 1 manuscript for re-evaluation that updates the plans for later studies accordingly, hence the current recommendation is labelled "Part 1".

 

URL to the preregistered Stage 1 protocol: https://osf.io/zh3w9 (under temporary private embargo)
 
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:

 

 

 

Castiglione, A., Brick, C., Esposito, G., & Bizzego, A. (2024). A climate action intervention to boost individual and collective climate mitigation behaviors in young adults. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/zh3w9

Surveys that measure self-report are a workhorse in psychology and the social sciences, providing a vital window into beliefs, attitudes and emotions, both at the level of groups and individuals. The validity of self-report data, however, is an enduring methodological concern, with self-reports vulnerable to a range of response biases, including (among others) the risk of social desirability bias in which, rather than responding honestly, participants answer questions in a way that they believe will be viewed favourably by others. One proposed solution to socially desirable responding is the so-called Bayesian Truth Serum (BTS), which aims to incentivise truthfulness by taking into account the relationship between an individual’s response and their belief about the dominant (or most likely) response given by other people, and then assigning a high truthfulness score to answers that are surprisingly common.

 

Although valid in theory (under a variety of assumptions), questions remain regarding the empirical utility of the BTS. One area of concern is participants’ uncertainty regarding incentives for truth-telling – if participants don’t understand the extent to which telling the truth is in their own interests (or they don’t believe that it matters) then the validity of the BTS is undermined. In the current study, Neville and Williams (2024) aim to test the role of clarifying incentives, particularly for addressing social desirability bias when answering sensitive questions. The authors will administer an experimental survey design including sensitive questions, curated from validated scales, that are relevant to current social attitudes and sensitivities (e.g. “Men are not particularly discriminated against”, “Younger people are usually more productive than older people at their jobs”). Three groups of participants will complete the survey under different incentive conditions: the BTS delivered alone in standard format, the BTS with an interim bonus payment that is awarded to participants (based on their BTS score) half-way through the survey to increase certainty in incentives, and a Regular Incentive control group in which participants receive payment without additional incentives.

 

The authors will then address two questions: whether the BTS overall effectively incentivises honesty (the contrast of BTS alone + BTS with interim payment vs the Regular Incentive group), and whether interim payments, specifically, further boost assumed honesty (the contrast of BTS alone vs BTS with interim payment). Regardless of how the results turn out, the study promises to shed light on the effectiveness of the BTS and its dependence on the visibility of incentives, with implications for survey design in psychology and beyond.

 

The Stage 1 manuscript was evaluated over two rounds of in-depth review. Based on ​detailed responses to reviewers’ and the recommender’s comments, the recommenders judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance.​​​

 

 

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:

 

 

Neville, C. M & Williams, M. N. (2024). Does Truth Pay? Investigating the Effectiveness of the Bayesian
Truth Serum with an Interim Payment: A Registered Report. In principle acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/vuh8b

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