“…For example, there is the wellestablished anisotropy between perceptual responses to horizontal and vertical disparity gradients. Perceived slant around a horizontal axis produced by vertical disparity gradients has a short latency and is close to prediction, whereas perceived slant around a vertical axis produced by horizontal disparity gradients is typically strongly underestimated, with surfaces perceived as much flatter than predicted geometrically (Gillam, Flagg, & Finlay, 1984;Fahle, & Westheimer, 1988;Mitchison & Westheimer, 1990;Gillam & Ryan, 1992;Cagenello & Rogers, 1993;van Ee & Erkelens, 1996;Pierce & Howard, 1997;Wardle, Palmisano, & Gillam, 2014). In addition, slant perception from horizontal disparity gradients is much slower than for vertical gradients (van Ee & Erkelens, 1996), emerging well after stereo fusion (Gillam, Chambers, & Russo, 1988).…”