What kind of illusion does it belong to when calligraphers write?

visual illusion. Calligraphers look at Chinese characters like fixed characters when writing, which is a visual illusion. Illusion refers to people's incorrect feelings or perceptions of external things. The most common is the illusion of vision. The reasons for the illusion are not only the influence of the characteristics of the objective stimulus itself, but also the physiological and psychological reasons of the observer.