No abstract

This study examined the responses of 40 undergraduate women and 40 men to two Poggendorff figures, a traditional figure with the right oblique line omitted and a modified variant with the left vertical line and the right oblique line absent. Participants placed a dot on the right vertical line where the oblique line, if extended, would intersect the right vertical line. The results showed that women displayed larger illusions than men on both figures, consistent with past findings. Finding a sex difference with the modified variant did not support the suggestion that the intersection between the oblique and vertical lines is responsible for such differences. The effects of spatial separation and size of acute angle were similar for both versions of the illusion. The effects of spatial separation were inconsistent with an explanation of the illusion based on depth cues and it was suggested that an explanation of the Poggendorff illusion should focus on processing between the vertical lines.