Correspondence effects for objects with opposing left and right protrusions.

Choice reactions to a property of an object stimulus are often faster when the location of a graspable part of the object corresponds with the location of a keypress response than when it does not, a phenomenon called the object-based Simon effect. Experiments 1-3 examined this effect for variants of teapot stimuli that were oriented to the left or right. Whether keypress responses were made with fingers within the same hand or between different hands was also manipulated. Experiment 1 showed that, for judgments of stimulus color and upright-inverted orientation, the Simon effect for intact teapots occurred in the direction of the spout location and was larger for within- than between-hand response modes. In Experiments 2 and 3, teapots with the handle or spout removed showed separate contributions of each component to the Simon effect. In Experiment 4, we clarified a discrepancy between our findings of object-based Simon effects and a previously reported absence of effect with color judgments for door-handle stimuli. We obtained an object-based Simon effect with respect to handle position when the bases of the door handles were centered but not when the handles were centered. The findings that object-based Simon effects occur with color judgments and when responses are fingers on the same hand are in closer agreement with a location coding account than with a grasping affordance account.