The objects of attention can be located anywhere along the causal link from the source of stimuli to the final output of the vision system. As causes, they attract and control attention, and as products, they constitute targets of analysis and explicit comments. Stimulus-driven indexing creates pointers that support fast and frugal cognition.

The notion of nonconceptual content in Dienes & Perner's theory is examined. A subject may be in a state with nonconceptual content without having the concepts that would be used to describe the state. Nonconceptual content does not seem to be a clear-cut case of either implicit or explicit knowledge. It underlies a kind of practical knowledge, which is not reducible to procedural knowledge, but is accessible to the subject and under voluntary control.