Table 1.

Selectivity of orientation tuning for Glass patterns

r	Selectivity index			Fraction significant
	Orientation	Quadropole		Orientation	Quadropole
λ/2	0.47	0.27	0.0001	37/79	4/79	0.0001
λ	0.33	0.35	0.701	8/66	15/66	0.169
	0.0002	0.013	Significance	0.0001	0.0038	Significance

We calculated an orientation and quadropole selectivity index (see Materials and Methods) for Glass pattern orientation tuning whenr ≈ λ/2 and r ≈ λ, the mean of which is shown in the four entries on the left side. The fraction of cells for which the selectivity index was statistically significant (see Materials and Methods) is shown in the four entries on the right side. We used a Wilcoxon test to assess the significance of the differences in selectivity index on the left, and a χ²homogeneity test for differences in the fraction of cells on the right. For each pair of entries, the probability value for the appropriate statistic is shown in italics below or to the right of the pair of numbers being compared. Both of the measures show that whenr ≈ λ, four-lobed tuning is present, but only two-lobed tuning appears when r ≈ λ/2. For comparison, the mean orientation selectivity index for gratings was 0.61, with 78 of 79 tuning curves significantly selective.