Theoretical note: Coordinate systems in visual word recognition

Marr and Nishihara (1978) have made certain recommendations about how representations postulated in a theory of visual information processing should be specified. Using this scheme the paper discusses representations which might be postulated in a model of visual word recognition. A representation is specified in terms of a set of primitives (e.g., word identities or visual features) in combination with a coordinate system. The coordinate systems considered are retinal, spatial (e.g., position on page) word-centred (position in word) and sentence-centred (position in sentence).

Various combinations of primitives and coordinate systems are considered along with how to decide which combinations are actually generated in the process of fluent reading. A tentative model is put forward in which a single processing stage, which starts anew after each saccade, generates a representation with word identities as its primitives and sentence-centred coordinates. Evidence to support such a model which has no intermediate representation with spatial coordinates is briefly reviewed.