 There is currently some dispute about whether the differences made by shifts of attention can be adequately characterized as differences in the content of the attended experience. If, as Watzl contends, they cannot, then phenomena of attention create a serious difficulty for any fully general attempts to explain the character of conscious experience by reference to the contents represented in it (Chalmers, 2004).  Such explanations might still be viable in circumscribed domains (Speaks, 2010).