What does the horizontal-vertical illusion show us about size perception?

Two experiments were carried out to investigate the horizontal-vertical illusion using the psychophysical method of adjustment and the double staircase method. Results from both experiments indicated that the eye movement and the stimulus time exposure can affect the magnitude of the illusion, but they cannot affect the illusion pattern in function of the location of the stimuli in the visual fields and of the location of vertical line on the horizontal line. It is suggested that size perception involves specialization of the right and the left brain