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 favorably by others. One proposed solution to socially desirable responding is the so-called Bayesian Truth Serum (BTS), which aims to incentivize 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 (Prelec, 2004).

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 (2025) tested the role of clarifying incentives, particularly for addressing social desirability bias when answering sensitive questions. The authors administered an experimental survey design (N=877) 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 completed the survey under different incentive conditions: the BTS delivered alone in a standard format, the BTS with an interim bonus payment that is awarded to participants (based on their BTS score) halfway through the survey to increase certainty in incentives, and a Regular Incentive control group in which participants receive payment without additional incentives.

The authors analyzed the effectiveness of the BTS through two registered hypotheses. First, the authors found that the BTS did not increase agreement with socially undesirable statements (compared to the control group), as theory would suggest, and even observed an opposite effect. This result, which could be confirmed by follow-up studies, raises some concerns about the robustness of the BTS method. Second, the authors conjectured that introducing an interim payment in the BTS mechanism would help reinforce its credibility in the eyes of the participants and would thus magnify its effect. However, the authors failed to detect a statistically significant difference between the standard BTS and interim-payment BTS mechanisms. Overall, the results of Neville and Williams (2025) call for some caution in the use of the BTS and for further work to better understand the contexts in which the BTS might be a useful tool to mitigate social desirability in surveys. 

This Stage 2 manuscript was evaluated over one round of in-depth review by two expert reviewers and a second round of review by the recommender. After the revisions, the recommender judged that the manuscript met the Stage 2 criteria and awarded a positive recommendation.

 

 

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. Neville, C. M & Williams, M. N. (2025). Does Truth Pay? Investigating the Effectiveness of the Bayesian
Truth Serum with an Interim Payment: A Registered Report [Stage 2]. Acceptance of Version 4 by Peer Community in Registered Reports. https://doi.org/10.31219/osf.io/s3znc

 

2. Prelec, D. (2004). A Bayesian truth serum for subjective data. Science, 306, 462-466. https://doi.org/10.1126/science.1102081

Does knowing more about others necessarily lead to greater liking, or might it breed contempt, as suggested by Norton et al. (2007)? In the current study, Horsham et al. (2025) tried to replicate and extend that original question. Collecting data from a large sample of U.S. undergraduates and employing carefully revised designs reviewed at Stage 1, they replicated Norton et al.’s initial studies (1a, 1b, and 2) while also adding new measures. Their primary aim was to see if the “less is more” effect, where increased familiarity decreases liking, would hold under rigorous modern standards, including pre-registration and several open science practices.

 

Results indicated that people indeed believe they will like someone more if they know more about that person, replicating Norton et al.’s initial finding from Studies 1a and 1b. However, the association between greater knowledge and reduced liking, the core of the “less is more” claim, was not consistently observed. Instead, the data showed little evidence that accumulating information inevitably decreases liking. Moreover, an added examination of curiosity as a potential mediator revealed that although curiosity and liking are positively related, curiosity itself was not strongly contingent on the amount of knowledge participants had. These findings help clarify why previous literature has sometimes presented mixed outcomes, and they underline the distinction between what people predict will happen and what actually does happen in forming impressions of others.

 

Peer review involved thorough evaluations by experts. Following multiple revisions through Stages 1 and 2, the manuscript has been deemed a carefully executed Registered Report, providing transparent methods, open data, and full reproducibility. It adds nuance to discussions around how knowledge, familiarity, and curiosity jointly shape our interpersonal attitudes. On this basis, 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/7mc4y
 
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. Norton, M. I., Frost, J. H., & Ariely, D. (2007). Less is more: The lure of ambiguity, or why familiarity breeds contempt. Journal of Personality and Social Psychology, 92, 97-105. https://doi.org/10.1037/0022-3514.92.1.97

 

2. Horsham, Z., Haydock-Symonds, A., Imada, H., Tai, H. C., Lau, W. L., Shum, T. L., Zeng, Y., Chow, K., & Feldman, G. (2025). Does learning more about others impact liking them?: Replication and extension Registered Report of Norton et al. (2007)’s Lure of Ambiguity [Stage 2]. Acceptance of Version 6 by Peer Community in Registered Reports.​ https://osf.io/ygkft

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

In interpersonal evaluation, the amount of information available about the other person has a significant impact. Norton et al. (2007) conducted systematic experiments suggesting a 'less is more' effect – that a lack of information leads to a more positive evaluation. However, subsequent studies have not always reached the same conclusion.

 

In the current study, Horsham et al. (2024) aim to address this issue by conducting direct and conceptual replications of the Norton et al. (2007) experiments, as well as additional extensive experiments focusing on the effects of curiosity. The authors seek to confirm in a reliable way the relationship between ambiguity and liking, and even to clarify the factors that mediate this relationship. The results should significantly advance our understanding of the importance of information management in interpersonal relationships.

 

The Stage 1 manuscript was peer-reviewed by two experts; after four rounds of review and based on their revisions and detailed responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 1 criteria and awarded it in-principle acceptance (IPA).

 

URL to the preregistered Stage 1 protocol: https://osf.io/7mc4y
 
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. Norton, M. I., Frost, J. H., & Ariely, D. (2007). Less is more: The lure of ambiguity, or why familiarity breeds contempt. Journal of Personality and Social Psychology, 92, 97-105. https://doi.org/10.1037/0022-3514.92.1.97

 

2. Horsham, Z., Haydock-Symonds, A., Imada, H., Tai, H. C., Lau, W. L., Shum, T. L., Zeng, Y., Chow, H. T., & Feldman, G., (2024). Does learning more about others impact liking them? Replication and extension Registered Report of Norton et al. (2007)’s Lure of Ambiguity. In principle acceptance of Version 4 by Peer Community in Registered Reports. https://osf.io/7mc4y