A MODEL OF VISUAL SPATIOTEMPORAL MEMORY - THE ICON REVISITED

With a minimal set of assumptions resulting from considerations about the perception of temporal structure, we argue for the existence of a spatio-temporal memory established by the mapping of time into simulta neous physical properties. The important point of this model is the di stinction between external, physical time and the internal representat ion of time. An immediate consequence of such a structure is the emerg ence of properties usually associated with the concept of iconic memor y or informational persistence. Some of these properties may hence be regarded as epiphenomena produced by the testing of a spatiotemporal s ystem with tachistoscopic spatial stimuli. The model can explain prope rties of the immediate memory span, that lack of effect of exposure du ration on tachistoscopic report, the partial-report superiority, the d ecay of iconic memory, and effects of a backward mask. It does not onl y avoid the incompatibility problems of the frozen-image concept in dy namic vision, but also provides an adequate basis for the processing o f time-varying scenes.