Correction to: Nature Neuroscience https://doi.org/10.1038/s41593-019-0377-4, published online 29 April 2019.
In the version of this article initially published online, labels in Fig. 6b,d were switched. Green dots should have been labeled “Artificial” and orange dots should have been labeled “Contrast”. The error has been corrected in the print, PDF and HTML versions of this article.