Fig. 6: Cross-temporal generalization of decoding luminance polarity versus hue.

a Classifiers were trained using the pattern of MEG activity elicited at time points from −200 ms to 600 ms after stimulus onset (y-axis) and tested using data not used in training across the same time interval, on the set of problems decoding luminance polarity generalizing across hue. The best decoding performance was achieved with classifiers that were trained and tested using data from the same time point after stimulus onset, indicated by the strong performance along the x = y diagonal. The peak classification time was at 100 ms; there was a dip in classification performance at about 120 ms. The black contours show regions in the heatmap that were p < 0.05 cluster corrected. The p values were obtained using a sign-permutation test. b Data as in a, but for classifiers trained and tested on the set of problems decoding hue generalizing across luminance polarity. The peak classification time was 119 ms; the cluster-corrected regions of significance extended further from the diagonal compared to a. c Comparison of results in a and b. The time points where the classifiers were more accurate for luminance polarity compared to hue are shown as dark blue (white contours show cluster-corrected significant results), while the time points where the classifiers were more accurate for hue compared to luminance polarity are shown as yellow (red contours show cluster-corrected results). The p values were obtained using a permutation test on the difference in accuracy between hue and luminance polarity decoding. The p values are cluster corrected. Decoding of hue showed greater generalization across time compared to decoding of luminance polarity, and the greater cross-temporal generalization for hue began relatively early after stimulus onset (~119 ms).