Studies of human depth perception using a reverse perspective illusion and its application to diagnostics in clinical medicine.

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This research project was worked on to explore top-down and bottom-up mechanisms of human depth perception using a reverse perspective illusion and to apply the findings to a diagnostics of a psychiatric disease in clinical medicine. Obtained results are described on below.Internal mechanism of the reverse perspective illusion was measured by fMRI. It was found that each brain area of BA19/39, BA37/19 and BA7 are strongly activated when the illusion is perceived. Further more, in case of the stimuli which has no pictorial cues for the illusion, as subjects made efforts to 'see' the illusion, activations were also found in frontal lobe. These results show the interactions between the top-down and the bottom-up processes during the illusion.To study the influence of the pictorial cues on the illusion, a paired comparison method and the binocular disparity adjusting method was applied to evaluate the strength of the illusion. These methods ware compared to the conventional method which me … More asure the distance between the subject and the reverse perspective object. The results show good agreements. It was confirmed that the newly developed methods can be used effectively to evaluate the strength of the illusion and influence of the pictorial cues.Psychological experiments to study basic properties of depth perception were performed. Eye movement, influence of body motion, surface perception from binocular disparity, depth perception from motion parallax, depth perception from 2D pictorial cues, were studied independently and made it dear about the basic property of depth perception.An experimental system using a stereo computer graphics technology was developed to present reverse perspective illusion by changing parameters (such as pictorial cues, geometrical factors, and binocular disparities). A perception experiment of the illusion was made to subjects of the sleep deprivation state using the system, and made it clear that the sensitivity to the perception of the illusion falls by sleep deprivation. This indicates the possibility of the application the results of the experiment to diagnostics of the psychiatric disease. Less