Measuring the Ponzo illusion with the method of production

The Ponzo illusion was varied as a function of angle of oblique arms and was measured by the method of production. The results showed that the method of production produced very similar results to those obtained by the method of limits. The data also indicated that relatively stable individual scores could be obtained if about six judgments were required and if the targets elicited a large illusion. It was concluded that the method of production should be given serious consideration when choosing a psychophysical method.