Abstract

This thesis is mainly concerned with the following two issues in mental imagery within the framework of the computational/representational theory of the mind. The first issue is about the mode of representation of mental images. The second issue is about the difference between mental images and the process of imagining, on the one hand, and propositional attitudes and the process of thinking, on the other. These issues are discussed in the context of current cognitive theories of mental imagery. ;With respect to the first issue, the picture-in-the-head theory of mental images is examined and rejected, Kosslyn's claim that mental images represent objects in the world more in the form of pictures than in that of descriptions is examined and rejected and the following proposition is defended: ;1. Cognitive psychologists have failed to provide a coherent account of mental images as pictorial, analog and quasi-pictorial mental representations; and the facts about mental images that have led people to postulate a different mode of representation for mental images, can be explained by a sentential theory of mental images. ;The second issue is discussed primarily in the context of Pylyshyn's tacit-knowledge theory of mental images. With respect to this issue, it is argued that Pylyshyn's tacit-knowledge theory of mental imagery cannot explain the regularities involved in the performance of the imagery tasks; so, the following proposition is presented and defended: ;2. Mental images are different from propositional attitudes and the process of imagining is different from the process of thinking in that only mental images and the process of imagining are governed by certain internal constraints. The internal constraints here are that certain spatial properties of objects must be represented together in a mental image; and that in contrast to the process of thinking, in imagining certain events, one has to go through the same internal states which one usually goes through during the perception of a similar event.