5 – Slant Perception

Publisher Summary A research on static slant judgments is useful in suggesting variables to be investigated in dynamic slant perception, but it is clear that the results obtained in the static case do not generalize directly to the dynamic case. Even for the few variables that have been studied in both static and dynamic displays, striking differences have been found. The dominance of perspective over form ratio in determining slant judgments is reversed when rotation to a slant is displayed. The increase in judged slant with increased texture regularity is absent when either rotation to a slant or the translation of a slanted surface along the axis of slant is displayed. Judged slant is close to displayed slant in most studies involving either of these transformations, in contrast to the underestimates of 50% or more found with static displays. These results, reinforced by the results obtained when motion and texture gradients are placed in conflict, suggest that motion overrides static indicators of slant, completely dominating slant judgments. The effects of disparity on slant judgments have not been compared to the effects of motion. When disparity and motion are separately compared to static perspective information, disparity does not seem to be dominant as motion, but this is only an indirect answer to the question of how conflicting motion and disparity information affect perceived slant.