Figure 7.

Effects of simultaneous SF pooling and spatial pooling are predicted by a model. (a) SF pooling causes an elongation of a left–right SF interaction map (SF_L–SF_R) by extending its extent along the 45° axis (outward pair of red arrows). But it also reduces the extent of the spatial (X_L–X_R) binocular interaction map along the −45° axis (inward pair of red arrows). Each column of low, opt., and high SF shows a binocular interaction map (top row) and its binocular SF interaction map (bottom row) for a binocular energy unit with low, optimal and high SF, respectively. Other parameters for each model are identical across subunits. Arrows in the SF interaction maps indicate the phase of IOPD tuning (figure 6, left). Since subunits are located at the same position, the phase is unchanged. (b) Conversely to (a), spatial pooling extends the spatial binocular interaction map (X_L–X_R) along the 45° axis (outward pair of blue arrows). But it also reduces the extent of the left–right SF interaction map (SF_L–SF_R) by canceling responses at upper left and lower right areas of the map (inward pair of blue arrows). The model pools subunits densely at many spatial positions, but for clarity is shown with three subunits: left, centre and right. Note that arrows in SF interaction maps depict the phase of tuning curves like those in figure 4d. They show complex patterns of rotation for left and right. These phase variations are the basis of response cancellation. (c) When SF pooling and spatial pooling are present simultaneously, effects from both on the spatial binocular interaction map (X_L–X_R) add up, causing further elongation (outward blue arrows and inward red arrows). (d) Binocular SF map (SF_L–SF_R) is shown. This map is also extended further by the constructive addition of effects from simultaneous SF and space pooling (outward red arrows and inward blue arrows).