The chambers in both experiments were lit only by blue lights within the Y-mazes; the only other light in the experiments came from the red headlamps worn by the experimenters. (A) Unedited still frame extracted from supplementary video 1 in Gagliano et al., 2016. (B) Unedited image of the Y-mazes used in Markel, 2020. (C) Panel A after histogram matching with panel B. The irregular rectangles are caused by the compression algorithm used in the original .mov file, and can be seen by adjusting the brightness and contrast on any frame extracted from that video. (D) Panel B after histogram matching with panel A. The histogram for each panel is shown in the bottom right corner; all histograms are 300 × 240 pixels, RGB, 281K; all images were processed as. png files for lossless compression. Image analysis was performed using the Fiji distribution of ImageJ Version 2.0.0-rc-69/1.52 n, Build: 269a0ad53f. The HistogramMatcher script is from the Fiji project CorrectBleach. This script was provided by Stack Overflow user Jan Eglinger, and is available in Supplementary file 1.