The enhanced processing account suggests that domain-specific expertise enhances the processing of information in that domain, such as enhanced color perception in visual artists and grapheme-color synaesthetes. A previous study (Ovalle-Fresa et al., 2021) found support for this account in both synaesthetes and non-synaesthete color experts; however, to fully understand the domain specificity of enhanced processing, other domains of expertise should be investigated and compared against each other in a double dissociation.

 

In this Stage 1 manuscript, Sachdeva et al. (2024) will investigate whether an enhanced processing account can explain domain-specific expertise in groups of color experts (i.e., visual artists) / grapheme-color synaesthetes and spatial experts (i.e., architects) / sequence-space synaesthetes. The spatial domain was chosen to compare to color since color and spatial processing recruit two distinctive cortical visual pathways: the ventral and dorsal streams, respectively. If enhanced processing is domain specific, then color experts / grapheme-color synaesthetes should show selective perceptual and memory performance enhancements for color tasks but not spatial tasks; and vice versa for spatial experts and sequence-space synaesthetes. The authors of this planned study further propose that perceptual performance should predict memory performance in the domain of expertise only; and that synaesthetes and non-synaesthetes with the same domain of expertise should perform similarly to each other.

 

To address these hypotheses, four independent groups will be recruited: grapheme-color synaesthetes, visual artists, sequence-space synaesthetes, and architects. Individuals with overlapping expertise and synaesthesia (e.g., visual artists who also have grapheme-color synaesthesia) will be excluded. Perception, short-term memory, and long-term memory for color (3 tasks) and space (3 tasks) will be assessed in all groups, and the authors will compare groups (synaesthetes, non-synaesthetes), domains of expertise (color, space), and task feature (color, space) in 2x2x2 linear mixed models. For all models, the authors predict that a significant interaction between domain of expertise and task feature will provide evidence for the domain specificity of the enhanced processing account. Additional analyses concerning working memory load (one, three, or five items) in the short-term memory tasks, and testing day (one, two, or three days post-training) in the long-term memory tasks, will be conducted to more deeply explore potential performance enhancements related to domain-specific expertise. Although these analyses may potentially provide additional evidence in favor of the hypothesized direction of effects, any deviation from predicted may pose a challenge for the interpretation of results. Nevertheless, this planned study is methodologically rigorous, and comprehensive in its aims.

 

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

 

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. Ovalle-Fresa, R., Ankner, S., & Rothen, N. (2021). Enhanced perception and memory: Insights from synesthesia and expertise. Cortex, 140, 14-25. https://doi.org/10.1016/j.cortex.2021.01.024

2. Sachdeva, D. & Whelan, E., Ovalle-Fresa, R., Rey-Mermet, A., Ward, J., & Rothen, N.. (2024). How perceptual ability shapes memory: An investigation in healthy special populations. In principle acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/6wn4m

 

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 Spatial-Numerical Association of Response Codes (SNARC) effect refers to the fact that smaller numbers receive faster responses with the left hand, and larger numbers with the right hand (Dehaene et al., 1993). This robust finding implies that numbers are associated with space, being represented on a mental number line that progresses from left to right. The SNARC effect is held to depend on relative number magnitude, with the mental number line dynamically adjusting to the numerical range used in a given context. This characterisation is based on significant effects of relative number magnitude, with no significant influence of absolute number magnitude. However, a failure to reject the null hypothesis is not firm evidence for the absence of an effect. In this Registered Report, Roth and colleagues (2024) report two large-sample online experiments, with a Bayesian statistical approach to confirm—or refute—a role for absolute number magnitude in modulating the classic SNARC effect (smallest effect size of interest, d = 0.15).

 

Experiment 1 closely followed Dehaene’s (1993) original methods, and found strong evidence for an influence of relative magnitude, and moderate-to-strong evidence against an influence of absolute magnitude. Experiment 2 was designed to exclude some potential confounds in the original method, and this second experiment found strong evidence for both relative and absolute magnitude effects, of comparable effect sizes (in the range of d = .24 to .42). This registered study demonstrates that the SNARC effect is not ‘fully flexible’, in the sense of depending only on relative number magnitude; it is also shaped by absolute magnitude.

 

This Stage 2 manuscript was evaluated by the recommender and one external reviewer. Following appropriate minor revisions, the recommender judged that the manuscript met the Stage 2 criteria for recommendation.

 

URL to the preregistered Stage 1 protocol: https://osf.io/ae2c8
 
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:
 

• Advances in Cognitive Psychology
• Collabra: Psychology
• Experimental Psychology
• Journal of Cognition
• Peer Community Journal
• PeerJ
• Psychology of Consciousness: Theory, Research, and Practice
• Royal Society Open Science
• Studia Psychologica
• Swiss Psychology Open

 
References

 

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

 

2. Roth, L., Caffier, J., Reips, U.-D., Nuerk, H.-C., Overlander, A. T. & Cipora, K. (2023). One and only SNARC? Spatial-Numerical Associations are not fully flexible and depend on both relative and absolute magnitude [Stage 2]. Acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/epnd4

How well animals may be able to cope with changes of habitat, specifically with rapid changes and thus novelty they encounter in an environment densely populated by humans, may be influenced by how they respond to novelty in general (Batisteli et al., 2022; Biondi et al., 2024; Castano et al., 2024; Heales et al., 2024). In considering this, it may be important to account for any difference in behavioural responses that animals exhibit when encountering a novel situation alone versus when they are doing so as part of a group.

 

Here, Allaert et al. (2025) tested how neophobia – the fear of unfamiliar objects – is affected by the social context in gulls, birds that are increasingly forced to live in urban environments due to the loss of natural coastlines. In this study, in which they reared herring gulls from egg and tested them taking into account that nestmates are not tested within the same groups, the authors found that the birds were faster to eat and spent more time in the zone of interest when they were tested in a group than when they were tested individually, specifically when a novel object was placed next to the food compared to when that object was a familiar one. The birds were also faster to enter the testing area when tested in a group, but this was not specific to the novel object condition. In addition to these changes in the average responses, the authors also report reduced variance when tested in a group in two of their three measures, namely in the latency to enter the testing area and time spent in the zone of interest.

 

The authors interpret their findings as being mostly in line with the ‘risk-dilution’ hypothesis, which is often considered in terms of predation risk (Krause & Buxton, 2002). They discuss possible reasons why other studies, with different species and different methodological setups, found support for alternative explanations.

 

The Stage 2 report was evaluated by the same two reviewers who had also reviewed the Stage 1 manuscript. In the revision, the authors focused on adding sex as a factor in their statistical models, which was the planned procedure for the statistical analyses in the Stage 1 report, and adding information regarding the problems encountered during testing and how these were handled. This specifically refers to the planned sample size (which the authors planned in the Stage 1 report taking into account both mortality and the fact that some birds would be not herring gulls but lesser black-backed gulls, which can only be established after hatching). However, there was higher than expected mortality, leading to a larger-than-planned overall reduction in sample size. During the study, the authors had contacted the recommender and discussed this issue, and the recommender advised on continuing the study and approved of the planned changes in the Stage 2 report. During the revision process, the authors added more information and also conducted an exploratory analysis, which included all birds, i.e. herring gulls and lesser black-backed gulls. This was suggested by a reviewer and the authors present this exploratory analysis in full in the supplemental material, while the main inferences are presented in the main text. In addition, during the Stage 2 review it became apparent that some minor details regarding the procedure would be useful to be included in the Stage 2 report, which the authors included in the Stage 2 revision. This did not alter the procedure as described in the Stage 1 report, but merely added more clarity to the text.

 

Based on detailed engagement with these points and the reviewers' comments, 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.

 

 

• Peer Community Journal
• PeerJ
• Personality Science
• Royal Society Open Science

 

 

1. Allaert, R., Knoch, S., Braem, S., Debeer, D., Martel, A., Müller, W., Stienen, E., Lens, L., & Verbruggen, F. (2025). Neophobia across social contexts in juvenile Herring gulls [Stage 2]. Acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/b58ha

 

2. Batisteli, A. F., Pizo, M. A., & Sarmento, H. (2022). Female neophobia predicts the use of buildings as nesting sites in a Neotropical songbird. Animal Behaviour, 183, 151-157. https://doi.org/10.1016/j.anbehav.2021.11.008

 

3. Biondi, L. M., Medina, A., Bonetti, E. A., Paterlini, C. A., & Bó, M. S. (2024). Cognitive flexibility in a generalist raptor: a comparative analysis along an urbanization gradient. Behavioral Ecology, 35, arae025. https://doi.org/10.1093/beheco/arae025

 

4. Castano, M. V., Zumpano, F., Biondi, L. M., & García, G. O. (2024). Does urbanization affect behavioral responses to novel objects in marine birds? The Olrog’s Gull as a case of study. Urban Ecosystems, 27, 427-437. https://doi.org/10.1007/s11252-023-01465-2

 

5. Heales, H. E., Flood, N. J., Oud, M. D., Otter, K. A., & Reudink, M. W. (2024). Exploring differences in neophobia and anti-predator behaviour between urban and rural mountain chickadees. Journal of Urban Ecology, 10, juae01. https://doi.org/10.1093/jue/juae014

 

6. Krause, J. & Ruxton, G. (2002). Living in Groups. Oxford University Press, USA.

Chronic pain is a major cause of disability that can often poorly managed with pharmacological treatments. This has prompted the exploration of other interventions like resizing illusions of body parts in augmented reality. These illusions have shown promise in conditions like osteoarthritis and complex regional pain syndrome, but it remains unclear how they alter the neural representation of body parts in the brain. The study by Hansford and colleagues aims to investigate these mechanisms in healthy participants, using somatosensory steady state evoked potentials (SSEP) and self-report questionnaires.

 

The study will involve finger stretching in an augmented reality setup that allows the researchers to independently manipulate visual and tactical stimulation. Assuming that multisensory stimulation indeed produces a robust illusion, the researchers will quantify the somatosensory evoked potentials in multisensory, unisensory, and two non-illusion control conditions. The study will provide inights into the neural mechanisms of these illusions and lay the ground for future investigations of these processes as a potential treatment for chronic pain.

 

The manuscript was evaluated over seven rounds of in-depth review by the recommender and three expert reviewers. After substantial revisions, 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/u6gsb
 
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. Hansford, K. J., Baker, D. H., McKenzie, K. J., & Preston, C. E. J. (2023). Somatosensory Response Changes During Illusory Finger Stretching. In principle acceptance of Version 7 by Peer Community in Registered Reports. https://osf.io/u6gsb