Do silhouettes and photographs produce fundamentally different object-based correspondence effects?

When participants classify pictures of objects as upright or inverted with a left or right keypress, responses are faster if the response location (left/right) corresponds with the location of a handle (left/right) than if it does not. This result has typically been attributed to a grasping affordance (automatic activation of muscles associated with grasping the object with the ipsilateral hand), but several findings have indicated instead that the effect is a spatial correspondence effect, much like the Simon effect for object location. Pappas (2014) reported evidence he interpreted as showing that spatial coding predominates with silhouettes of objects, whereas photographs of objects yield affordance-based effects. We conducted two experiments similar to those of Pappas, using frying pans as stimuli, with our two experiments differing in whether the entire object was centered on the display screen or the base was centered. When the objects were centered, a positive correspondence effect relative to the handle was evident for the silhouettes but a negative correspondence effect for the photographs. When the base was centered, the handle was clearly located to the left or right side of the display, and both silhouettes and photographs produced correspondence effects of similar size relative to the handle location. Despite the main results being counter to the grasping affordance hypothesis, response-time distribution analyses suggest that, instead of activating automatically at fast responses, an effector-specific component of the hypothesized type may come into play for responses that are selected after the handle location has been identified. [ABSTRACT FROM AUTHOR]