EVIDENCE FOR THE VIEW THAT TEMPOROSPATIAL INTEGRATION IN VISION IS TEMPORALLY ANISOTROPIC

In two experiments low-pass and high-pass spatially filtered versions of a base image were prepared and the effect of the order of delivery of sequences of filtered and base images investigated. A task that req uired subjects to discriminate 120 ms presentations of a full-bandwidt h base image and degraded sequences that contained sets of three diffe rent spatially filtered versions, or mixtures of spatially filtered an d full-bandwidth versions of the image, were used. Each set of images used in the degraded sequences was presented either so that within the 120 ms presentation window the spatial content swept from low to high spatial frequencies or from high to low, In experiment 1 twenty subje cts discriminated between a base image and degraded sequences of an ur ban scene. Results showed both a significant overall effect of image o rder, with low-to-high spatial-frequency information delivery being mi staken more often for the full-bandwidth presentation than high-to-low , and that different sets of degraded image sequences varied significa ntly in the frequency with which they were mistaken for the full-bandw idth presentation. In experiment 2 a base and filtered versions of a h uman face were used in an identical task with twenty different subject s and a very similar pattern of significant results was obtained, alth ough imposed on a lower overall error frequency than that obtained in experiment 1. It was concluded that the results of both experiments pr ovide evidence for an anisotropic temporospatial integration mechanism in which availability of spatial information in a low-to-high spatial -frequency sequence results in more efficient integration than a high- to-low.