THE GLOBAL FIGURAL CHARACTERISTICS IN THE ZOLLNER ILLUSION

The Zollner illusion has been accounted for in terms of local interact ions between the vertical lines and the crossing segments. Recently, h owever, some evidence supporting the importance of global figural char acteristics-ie of figural elements that are not directly interacting w ith the test lines-in the occurrence of orientation illusions has been reported. Three experiments have been conducted with parts of the Zol lner figure to test whether this illusion is affected by the global fi gural characteristics. The results indicate that, similarly to what ha s been observed for other orientation illusions, the Zollner illusion depends on both local and global characteristics of the stimulus confi guration. In addition, results suggest a similar weight for both these figural characteristics in determining the occurrence of the illusory effect. Finally, relations among different orientation illusions are also discussed.