 Representationalists about qualia are often also externalists about representational content (but not always — see, for example, Chalmers 2004). On this view, what a given experience represents is metaphysically determined at least, in part, by factors in the external environment. Thus, it is usually held, microphysical twins can differ with respect to the representational contents of their experiences. If these differences in content are of the right sort then, according to the wide representationalist, microphysical twins cannot fail to differ with respect to the phenomenal character of their experiences. What makes for a difference in representational content in microphysical duplicates is some external difference, some connection between the subjects and items in their respective environments. The generic connection is sometimes called ‘tracking’, though there is no general agreement as to in what exactly tracking consists.