Taiichiro ISHIDA and Mitsuo IKEDA

School of Architecture, Faculty of Engineering, Kyoto University, Yoshidahonmachi, Sakyo-ku, Kyoto, 606-01 Japan

(Accepted September 29, 1994)

We examined the tolerance of full-field illuminance changes to perceive constant illumination on the picture across saccades. In the experiment, subjects observed a picture of an actual scene, while the illuminance on the picture was alternated between E and E?^DE whenever subjects made saccades. The subjects reported whether they noticed any changes in brightness or color in the picture. Thresholds for detecting illumination changes were measured at three illuminance levels. It was shown that the thresholds amounted to 40% decrement of illuminance on average, indicating there exists fairly large tolerance of additional illumination changes across saccades. It was also found that the illumination changes were less noticeable at lower illuminance levels.

Key words : vision, saccade, visual stability, illumination, tolerance