Fig 1. Example stimulus texture patterns in the experimental design.

Textures were composed from DoG (Difference of Gaussian) micropatterns. Each stimulus texture was assigned one of three element spacing levels (top row), one of three element size levels (middle row), and one of five element jitter levels (bottom row), for a total 3 × 3 × 5 = 45 conditions, and 1035 possible combinations of pairs ((44 × 45)/2 + 45) = 1035), including 45 same-condition pairs. Examples of 11 out of 45 conditions are depicted here. In the top row of stimuli, spacing level is 1 to 3 from left to right (small to large) at size level 3 and jitter level 2. In the middle row, both spacing level and jitter level are 3, and size level is 1 to 3 from left to right (small to large). In the bottom row, both spacing level and jitter level are 2, and jitter level is 1 to 5 from left to right (more regular to more irregular).