Tactual illusions.

16 college males participated in a study exploring active and passive illusions in touch. Analogs to 2 primary and 2 secondary visual illusions were constructed for active and for passive tactual presentation. Tactual illusory effects similar to those one would predict from vision were found in the active mode of presentation of the Müller-Lyer, and horizontal-vertical conditions, while opposite effects were found in the active mode of presentation of a modification of Delboeuf circles and in the passive diamond-square and horizontal-vertical conditions (ps less than .02). Analogous primary and secondary illusory results interacted with the active and passive modes of presentation.