(A) Stimulus construction. Texture patterns were computed by modulating two orthogonal luminance gratings (the carriers, with ±45° orientations) with a third vertical or horizontal modulator grating of lower spatial frequency. A fixed orientation difference of ±45° separated the carriers and modulator. The contrast-modulated carrier patterns were summed, and the result was multiplied by a circular window with raised-cosine smoothed edges. Mean luminance was constant across the stimulus. (B) Stimulus conditions. Two spatial frequencies were used for both the 1st-order carrier (low/L and high/H: 2 and 4 cycle/deg) and 2nd-order modulator (low/L and high/H: 0.5 and 1 cycle/deg), resulting in four texture conditions: LL, HL, LH, and HH.