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