 Whether or not a theory of attention can be turned into a non-circular explanation of demonstrative reference, the idea that attention and reference are related does seem to cast light on what goes on when we understand referring expressions. Campbell’s examples succeed in suggesting that what we attend to and what we refer to are often the same. There is also some empirical evidence, coming from developmental psychology, indicating that attention-related abilities play a crucial role in the infant’s development of an understanding of its caregiver’s demonstrative use (see  Section 3.3).  Lessons have been drawn from this that are not only about the comprehension of linguistic expressions. This developmental work has also been taken to imply something about our grasp on directly referring thoughts. The idea here – as in the work of Dickie and Campbell – is not only that attention contributes to our production and comprehension of linguistic expressions that have particular referents, but that it also contributes to the establishment of those referents as the contents of our thoughts. In addition to these developmental considerations, Michael Barkasi has suggested that the nature of attention’s contribution to fixing the reference of thoughts can be illuminated by considering the pattern of neural projections to the frontal eye fields. Whereas Campbell characterizes attention in epistemic terms, Barkasi favours a sub-doxastic characterization, in which attention ‘sets targets’ and thereby regulates the flow of visual information (Barkasi, 2019).