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shaft, the apparent elongation of the wings-out figure decreases and the apparent contraction of the wings-in figure changes to apparent elongation. Worrall and Firth (1974) reported a different pattern of illusion change for two-wing B /.> Mtiller-Lyer figures containing wings at only one end of the shaft. Whereas moving the wings away from the shaft decreased the magnitude of the wings-in illusion, it changed the wings-out illusion from apparent elongation to c apparent contraction. The effect of wing displacement upon the Mtiller-Lyer illusion was measured in three experiments. Illusion magnitude was assessed by obtaining judgments of either the length (Experiment 1) or the ap-D parent midpoint (Experiments 2 and 3) of the shaft of fourwing (Experiment 1), two-wing (Experiments 1-3), and one-wing (Experiments 1 and 2) Mtiller-Lyer figures. Both measures of the illusion showed that displacement of the wings away from the shaft had similar effects on the fourand two-wing Mtiller-Lyer figures. The results are discussed in the context of assimilation theories of the Mtiller-Lyer illusion, and a possible reason for the apparent inconsistency between Worrall and Firth's conclusions and the present findings is outlined.