Figure 6.

V2 stripe-types distinguished by vector magnitude and orientation gradient. (A) Normalized average orientation vector magnitude versus normalized orientation gradient for 4 stripe-types in Case 2. The 4 stripe types form 2 clusters. The thin and type-I interstripe cluster is characterized by low orientation selectivity and high orientation gradient. The thick and type-II interstripe cluster is characterized by higher orientation selectivity and lower orientation gradient. (B) Normalized average orientation vector magnitude versus normalized orientation gradient for 4 stripe-types in Case 3. Compared with Case 2, the type-I interstripe in Case 3 had lower orientation selectivity, giving the appearance of a weaker clustering with the thin stripe. See text for details. (C) Normalized average orientation vector magnitude versus normalized orientation gradient for 4 stripe-types across all 4 cases. (D) Plot of the probability values associated with a priori pair-wise comparisons (Wilcoxon's rank sum test) of orientation vector magnitude and orientation gradient magnitude between stripe-types across 4 cases. Dashed lines indicate P < 0.05 value for each metric. Three of the 6 stripe-type comparisons were statistically significant for both orientation selectivity and gradient magnitude and thick stripes and thin stripes were only distinguishable by orientation selectivity. The comparisons of thick stripes versus type-II interstripes and thin stripes versus type-I interstripes were not significant for either orientation selectivity or gradient.