When offered a range of options and asked to make multiple selections, how do people choose? Over the last 30 years, a key finding to emerge from behavioural economics is that people distribute their choices more evenly than would be considered optimal – a phenomenon termed “diversification bias” or the “diversification heuristic” (Read & Loewenstein, 1995). For example, when filling a plate from a buffet, you might be inclined to choose a relatively even amount of everything on offer, even when you prefer some foods over others. Similarly, when allocating savings among different investment options, people are prone to spreading their money more evenly than would maximise utility.

 

In an influential study, Fox et al. (2005) found that diversification bias can be shaped by so-called “partition dependence” – the tendency to allocate resources differently across options depending on how they are subjectively grouped. Such groupings could be arbitrary; so, for example, to return to the buffet example, people might diversify across high-level categories such as cooked and uncooked, savoury and sweet, or surf and turf, and then diversify across the options within those categories. The nature of level of these subjective (and potentially arbitrary) categorisations can strongly influence the final allocation of resources. Diversification bias and partition dependence have important implications for basic theory in judgment and decision-making as well as applications in behavioral economics and finance.

 

In the current study, Li and Feldman (2022) propose to replicate Studies 1, 2 and 5 from Fox et al. (2002) in a large online sample. In particular, they plan to ask how partitioning influences the allocation of choices between options, and the extent to which partition dependence is reduced in people with greater relevant expertise. The authors also propose extending the original study to explore individual differences in the desire for choice diversity as predictors of partition dependence.

 

The Stage 1 manuscript was evaluated over one round 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).
 
URL to the preregistered Stage 1 protocol: https://osf.io/bx8vq

 

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:
 

• Advances in Cognitive Psychology
• Experimental Psychology
• F1000Research
• Journal of Cognition
• Meta-Psychology
• Peer Community Journal
• PeerJ
• Royal Society Open Science
• Swiss Psychology Open

 
References

 

1. Read, D., & Loewenstein, G. (1995). Diversification bias: Explaining the discrepancy in variety seeking between combined and separated choices. Journal of Experimental Psychology: Applied, 1, 34-49. https://doi.org/10.1037/1076-898X.1.1.34

 

2. Fox, C. R., Ratner, R. K., & Lieb, D. S. (2005). How subjective grouping of options influences choice and allocation: Diversification bias and the phenomenon of partition dependence. Journal of Experimental Psychology: General, 134, 538-551. https://doi.org/10.1037/0096-3445.134.4.538

  
3. Li, M. Y. & Feldman, G. (2022). Revisiting diversification bias and partition dependence: 
Replication and extension of Fox, Ratner, and Lieb (2005) Studies 1, 2, and 5, in principle acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/bx8vq

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 

While cerebral lateralisation for oral language is well-characterised, cerebral lateralisation for written language is much less well-understood. In this study, Papadopoulou et al. (2022) will use functional transcranial Doppler ultrasonography to assess lateralisation for written language in 7- to 9-year-old children at risk for dyslexia and neurotypical children. They will use tasks that assess efficiency in reading and writing names as well as speed and fluency in writing. The findings of this manuscript will highlight whether children with dyslexia showed atypical lateralisation for language in a written task. In addition, the authors plan to explore the correlation between lateralisation and writing competence. 

 

The Stage 1 manuscript was evaluated over two rounds of in-depth review. Based on the edits made to the manuscript, and detailed responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance (IPA).

 

URL to the preregistered Stage 1 protocol: https://osf.io/u54tk (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:
 

 

References
 

1. Papadopoulou, A.-K., Vlachos, F., Pervanidou, P., Anesiadou, S., Antoniou, F., Phylactou, P., Badcock, N.A. & Papadatou-Pastou, M. (2022). Cerebral lateralization of writing in students at risk for dyslexia using functional Transcranial Doppler ultrasonography, in principle acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/u54tk (under temporary private embargo)

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

The human capacity and need for play has been recognized as a central psychotherapeutic component for a long time (e.g. Winnicott 1971). More recently, experts have started developing specialized digital gameplay to be used as therapeutic tools and even utilizing existing videogames for similar purposes (see Ceranoglu 2010). On the other hand, the concerns about some players becoming overinvolved in videogames also led the World Health Organization to include “gaming disorder” in the 11th edition of the International Classification of Diseases, which echoes the nuance required to address human-technology relationships in general.  
 
In the present registered report, Billieux et al. (2024) make use of analog structured role-play in a new intervention aiming to mitigate social anxiety and problematic gaming patterns in online gamers. The authors carried out an exploratory pilot to test a 10-week protocol over three modules inspired by the well-known Dungeons & Dragons franchise. Through a multiple single-case design with a 3-month follow-up, the authors carried out the pilot with 20 participants (two dropped out), which enabled collecting valuable early data about the feasibility and potential of the intervention. 
 
Weekly psychometric assessments indicated that the intervention may support participants and it should continue to be studied in order to comprehensively evaluate its effectiveness. Feedback obtained from participants and other parts of the pilot project enabled identifying elements (e.g., difficulty adjustments), which can be given attention usefully in intervention development. Without question, the study by Billieux et al. (2024) is to be commended for highly transparent documentation of the project, which allows future researchers and intervention developers to learn from the pilot beyond initial results. Among other relevant materials, the supplements provide a detailed case study and item-level psychometric reporting, which can help the development of technical solutions and new hypotheses.
 
Taken together, the study by Billieux et al. (2024) paves the way for open science invention piloting in the field. The Stage 2 manuscript was evaluated by three experts (areas: experimental methods, psychopathology, gaming) via in-depth peer review across two rounds. 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/h7qat

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: 

 

• Collabra: Psychology
• F1000Research
• Peer Community Journal
• PeerJ
• Royal Society Open Science
• Swiss Psychology Open

 

References
 
1. Billieux, J., Fournier, L., Rochat, L., Georgieva, I., Eben, C., Malmdorf Andersen, M., King, D., Simon, O., Khazaal, Y., Lieberoth, A. & Blocha., J. (2024) Can playing Dungeons and Dragons be good for you? A registered exploratory pilot program using offline Tabletop Role-Playing Games (TTRPGs) to mitigate social anxiety and reduce problematic involvement in multiplayer online videogames [Stage 2 RR]. Acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/z32d5

 

2. Ceranoglu, T. (2010). Video Games in Psychotherapy. Review of General Psychology, 14 (2). https://doi.org/10.1037/a0019439

 

3. Winnicott, D. (1971/2009). Playing and Reality. Routledge.