Comparison of empirical predictions and psychophysical results for moving lines seen in a triangular aperture. (A) The aperture. (B) The frequency of occurrence of 2-D directions of line sequences constrained by a triangular aperture. As before, the green arrows indicate the results of psychophysical testing and the red arrows are the empirical predictions. The perceived directions differ systematically from the direction normal to the line orientation for orientations that are not 45º, increasing for larger angles. These biases are again closely predicted by the empirical data. (After Sung et al., 2008)