Classical Illusions from Parallel Line Figures: Evidence for Interactions among Length-Coding Neurons

Abstract

Variations of the Craik-O'Brien, Müller-Lyer, reversed Müller-Lyer, orthogonal Müller-Lyer, and Ponzo illusions were created using 10 to 12 parallel lines. 20 participants judged which of two physically equal lines in the patterns appeared longer. For 4 of the 5 patterns, the parallel lines created illusions which corresponded to those produced by the template figures. The results suggest that length is encoded by frequency of neural response and that the parallel line illusions, as well as their classical counterparts, emerge from interactions which distort this frequency code.