With the advance of multimedia technology, the frequency of exposure to artificial visual information has been increasing. The physiological damages caused by visual information which is fewer conformable to human brain has become a serious social problems. We must take into account the fact that visual information mediated by electronic communication systems has different characteristics compared to those of natural information. The granularity of an image presented via a visual medium depends on the resolution of the medium, and it differs from that of the original image. We investigated human KANSEI reactions to the difference in visual granularity by using recorded electroencephalographic alpha activity and the Scheffe' s paired comparison method, based on our previously developed methods. Our results suggest that finer visual images having a fractal structure increase the occipital activity in alpha EEG and give better impression than rougher images.
