Cells tuned to horizontal-orientation can still encode horizontal disparity. The sketches show a horizontally-oriented receptive field in the left and right retina, with a bar stimulus superimposed. In A, the bar has zero disparity and falls over the ON subregion of the receptive field in both eyes, resulting in a high firing rate. In B, the disparity has been increased until the bar has moved off the receptive field in both eyes, so the cell does not respond. The cell thus encodes horizontal disparity in fundamentally the same way as a vertically oriented cell would, the only difference being that its disparity tuning curve has a larger spatial scale.