Fig. 2: Cardinal anisotropies for orientation decoding are specific to central stimuli in EEG. Stimulus positions and sizes (top) are shown to scale.
From: Model mimicry limits conclusions about neural tuning and can mistakenly imply unlikely priors
Dashed lines depict the vertical and horizontal meridians. Black horizontal line illustrates 10° visual angle from fixation. A Re-analyzes of experiments reported by Harrison and colleagues1 (left: n = 36) and Wolff and colleagues23 (right: n = 24) where central orientations were shown to participants. Line plots show mean-centered Mahalanobis distance-based decoding metrics as a function of orientation, with shaded areas indicating the cardinal orientation bins used to compute differences between horizontal (green) and vertical (purple) orientations. Blue error areas are 95% confidence intervals (C.I.). The box plots show decoding metric differences for horizontal minus vertical orientations, with box limits indicating the upper and lower quartiles of the data, whiskers indicating 1.5 times the inter-quartile range, and blue dots representing individual subjects. The superimposed black circle and error-bars indicate the mean and 95% C.I. Top: Mean-centered accuracy (mean-centered cosine vector mean of pattern similarity curve), Middle: Mean-centered precision (1 minus the circular standard deviation of decoded orientation across trials), Bottom: Bias of pattern similarity curves, in degrees. Both data-sets show statistically significant differences between horizontal and vertical orientations), with higher decoding for horizontal orientations (both p < 0.001), higher precision for horizontal orientations (left: p < 0.001, right: p = 0.003), and a stronger attraction toward vertical orientations (both: p < 0.001). Tests were two-sided permutation t-tests (10.000 permutations). No adjustments for multiple comparisons were made. B Re-analyzes of experiments with orientations presented laterally24,25 (left: n = 30; right: n = 26) to the left and right of fixation, at an eccentricity of 6.69° or 6.08° (for data from24 and25, respectively). Same conventions as in A. No consistent differences between horizontal and vertical orientations. (Decoding accuracy difference, left: p = 0.315, right: p = 0.232; precision difference, left: p = 0.837, right: p = 0.895; attraction difference, left: p 0.43, right: p = 0.236; two-sided, not corrected for multiple comparisons). Source data are provided as a Source Data file.
