Visual misalignment in arc and chevron figures.

Five experiments investigated an apparent misalignment effect in 90 degrees arc figures. Preliminary observations showed that the effect occurs also in chevron figures, in an afterimage of the arc figure, and haptically in arc- and chevron-shaped objects. The experiments showed that the effect is greater with 3 radial lines than with 2, absent without them, and present in a figure consisting of only 3 radial lines. The effect with arc figures was consistently greater than that with chevron figures, a difference found not to be due to an apex marking the midpoint of the latter, and it was of intermediate size in figures with 1 arc boundary and 1 chevron boundary. The misalignment was also greater in narrow, elongated figures. The issues singled out for discussion are the effect of context on the misalignment effect with 3 radial lines, a possible explanation in terms of perceptual compromise, the difference in the effect between arcs and chevrons, and the relationship between this illusion and the Morinaga illusion.