Figure 5.

Contrast threshold for identifying the orientation (horizontal vs. vertical) of three parallel global contours consisting of small local Gabor elements. Thresholds were determined in three stimulus conditions. The local elements were either all aligned with or all orthogonal to the global contour or they could be both aligned and orthogonal (i.e., mixed). Only one sampling rate (100%) was used. (A) The three observers’ individual thresholds. (B) Contrast thresholds in the stimulus conditions of aligned and orthogonal Gabor orientations were normalized with respect to the thresholds when the Gabor orientations were mixed. The columns represent the means of the three observers.