Abstract
Previous work has suggested that targets from separable dimensions, such as color and shape, can coactivate responses. This contrasts with the “race” that occurs between targets from the same dimension. Assuming, for example, that the targets are red and X, a red O and green X would coactivate the response, whereas two red Os or two green Xs would participate in a race to activate the response. However, instead of focusing on the number of dimensions that contain targets (two vs one), it could alternatively be argued that the critical difference concerns the number of objects (one vs two). When multiple targets are from the same d imension, they must be processed as distinct objects. When targets are from different dimensions, they may be combined into a single object. Under this view, for which we have found some very strong evidence, coactivation occurs within objects and not between dimensions.