In order to be raise the accuracy of the TAM network (Topographic Attentive Mapping network) structure, which is. analogous to visual system, we need discuss how to provide it a simultaneous description of the receptive field. Aperture experiments are used for observing the mechanism of visual system. Nishina et al. claim that the perceptual grouping strongly depends on the length of display time and argue that the processing of visual computation tasks, as in aperture experiment under iterative processing, is not as far as when processing other tasks. This paper affirms Nishina's claim and describes more detail experiments under a wider variety of conditions. Most of the results of our experiments support Nishina's claims, however, we encountered a potential new finding: we found some regularity in the decrease of the perceptual rate at more delayed speeds of the lines' motion.