Reaction time, bilateral differences, and the Poggendorff and Ponzo illusions

12 subjects responded with either hand to tachistoscopically presented Poggendorff and Ponzo figures in both their right and left visual fields. Reaction time decreased as illusory magnitude increased for both figures. Reaction time was faster for both figures when presented in the right visual field and showed a pattern characteristics of a dichotomous encoding strategy, while the reaction time for the figures presented in the left visual field followed a pattern characeristic of magnitude estimation.