In this chapter, I outline my answer to the question of how people use their visual perception in the performance of report tasks. In answering this question, I use the fortunate fact that there is a close correspondence between what has been said in the experimental literature of the past about the implementation of an instruction for task performance and what Turing (1936) has said about the performance of a computation on a sheet of paper (see Chapter 3, especially Section 3.4). The exposition presented in this chapter is not intended to be complete nor even to be correct in all theoretical details and for all experimental circumstances; in further chapters my answer is reﬁned, elaborated, and extended. The purpose of this chapter is mainly didactic. It presents the core of my answer plus some further theoretical arguments that, in my view, strengthen my theoretical position.