Extensive research has identified individual differences associated with sex in a range of visual task performances, including susceptibility to visual illusions. The aim of this study was to identity the locus of sex differences within the context of the Poggendort illusion. 79 women and 79 men participated within a mixed factorial design. Analyses indicated that sex differences were only present in the stimulus con text with the full inducing clement present. This finding replicates recent research and provides qualifying evidence as to the locus of the effect. The findings are discussed within the functional framework of perceptual processes involved in extrapolating 3 dimensional characteristics from 2 dimensional visual stimuli.