日比野 治雄

Patients with migraine are susceptible to visual discomfort. Some painters who suffer from migraine express their migraine experience and visual discomfort through their paintings, which we refer to as migraine art. Several famous painters (e.g., Picasso) also have been reported to suffer from migraine; therefore, we refer to their paintings as "possible-migraine art." Although paintings with excessive energy at mid-spatial frequencies are uncomfortable to view, it remains unknown whether migraine art and possible-migraine art contain spatial characteristics that contribute to visual discomfort. We performed a spatial-frequency analysis on migraine art, possible-migraine art, and non-migraine art images. The results revealed that migraine art contains more energy at mid-spatial frequencies than non-migraine art. Possible-migraine art also contains this spectral characteristic. We propose that painters who suffer from migraine may utilize rather than avoid spatial characteristics that contribute to visual discomfort.

Shading is one of the typical depth cues generally used in letter illustrations and designs. Among the various kinds of shading directions, we humans are most familiar with shading in the right-bottom direction. In the present study, we investigated the perceptual effects of the shading directions using letters of alphabets as stimuli. In Experiment 1, we used 26 capital letters and 4 geometric figures in the six shading directions, which means that there were 180 conditions (i. e., (26 letters +4 figures) ×6 shading directions). For each condition, we measured the reaction times for perceiving the stimulus. The results indicated that it takes longer for subjects to recognize simple letters and figures. In Experiment 2, we focused on preferences and readabilities of the stimuli, using eight capital letters in four shading conditions. As the results, we found that the right bottom shading was evaluated as the highest (i. e., the most beautiful, positive, and readable). It is plausible that the results are related to our familiarities with the right bottom shading.