It is time to clamp down on the use of misleading rainbow colour scales that are increasingly pervading the literature and the media (see http://tiny.cc/endoftherainbow). Accurate graphics are key to clear communication of scientific results to other researchers and the public — an issue that is becoming ever more important.
Aside from the challenge they pose for colour-blind readers (S. C. Allred et al. Nature 510, 340; 2014), spectral-type colour palettes can introduce false perceptual thresholds in the data (or hide genuine ones); they may also mask fine detail in the data (D. Borland and R. M. Taylor Comput. Graph. Appl. 27, 14–17; 2007). These palettes have no unique perceptual ordering, so they can de-emphasize data extremes by placing the most prominent colour near the middle of the scale.
These issues can have profound consequences: for example, changing to a non-rainbow colour scale improved diagnostic accuracy for heart disease (M. Borkin et al. IEEE Trans. Vis. Comput. Graph. 17, 2479–2488; 2011).
Journals should not tolerate poor visual communication, particularly because better alternatives to rainbow scales are readily available (see, for example, go.nature.com/zvouhq and http://colorbrewer2.org). We urge all journals to stipulate in their guidelines that graphics must convey accurate and accessible information.
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Hawkins, E. Scrap rainbow colour scales. Nature 519, 291 (2015). https://doi.org/10.1038/519291d
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