Visual discomfort and variations in chromaticity in art and nature

SH was supported by a NARSAD Young Investigator Grant from the Brain and Behavior Research Foundation (26282), an R15 AREA award from the National Institute of Mental Health (122935), an NSF EPSCoR grant (1632849) on which SH is a co-investigator, and the NIH COBRE PG20GM103650. OP was partially funded by a Leverhulme grant (RPG-2019-096) to Julie M. Harris and a Research Incentive Grant from the Carnegie Trust (RIG009298).Visual discomfort is related to the statistical regularity of visual images. The contribution of luminance contrast to visual discomfort is well understood and can be framed in terms of a theory of efficient coding of natural stimuli, and linked to metabolic demand. While colour is important in our interaction with nature, the effect of colour on visual discomfort has received less attention. In this study, we build on the established association between visual discomfort and differences in chromaticity across space. We average the local differences in chromaticity in an image and show that this average is a good predictor of visual discomfort from the image. It accounts for part of the variance left unexplained by variations in luminance. We show that the local chromaticity difference in uncomfortable stimuli is high compared to that typical in natural scenes, except in particular infrequent conditions such as the arrangement of colourful fruits against foliage. Overall, our study discloses a new link between visual ecology and discomfort whereby discomfort arises when adaptive perceptual mechanisms are overstimulated by specific classes of stimuli rarely found in nature.Publisher PDFPeer reviewe

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Data and analyses for the articl

An electrically coupled pioneer circuit enables motor development via proprioceptive feedback in Drosophila embryos

Raw data described in the main text and the supplemental information

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Neuroimaging and eye tracking dat

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One way to cooperate with others and avoid exploitation is reciprocal cooperation. Reciprocity is the selective helping of those who were cooperative before, which is commonly based on outcomes. Yet, outcomes may not reflect intentions, that is if an individual is unable but willing to help. Humans, including children, show such intention-based reciprocity. However, it is unclear whether other animals consider intentions in reciprocal settings. Here, I tested whether Norway rats (Rattus norvegicus) reciprocate help based on intentions by manipulating the outcome while keeping the partner's cooperative intentions the same. Subjects experienced a partner that was able to help by providing food via a movable platform. In another condition, the same partner was unable to help because the platform was blocked. When the roles were exchanged afterwards, subjects provided food more often to “able” than “unable” partners, even though the latter attempted to help. I compared these findings to data using “willing” and “unwilling” partners that were able to help. Again, rats based their cooperative behaviour on outcomes rather than the intention to help. This suggests that rats reciprocate primarily based on outcomes and seem to not consider cooperative intentions. Although subjects provided consistently less food to partners that did not help, they provided them with some help. Potentially, rats use a cognitively less demanding strategy by helping defectors a bit to maintain cooperation. Thereby, cooperation might be resistant to situations in which an apparent defector was actually unable to help, but had cooperative intentions and might be a good cooperation partner in the future