to other stimulus types had overlapping, but dissociable, scalp topographies. Whether this means there is more than one “N400” is difficult to answer based on surface potentials alone because of possible temporal overlap with other responses. At a deeper level, the answer depends on what is meant by different, and, as such, is theoretically laden. Early on, when the field was dominated by the information processing framework, assuming seriality and modularity of processes, topographic differences were often regarded as suggestive of different processors. However, as the field moved toward more distributed and interactive views, distributional differences were likely to be treated in a graded rather than categorical fashion.
