A unified model of spatial and object attention based on inter-cortical biased competition

We present a physiologically constrained neural dynamical model of the visual system for the organization of attention and its mediation of object recognition and visual search. In this model, spatial and feature attention are mediated by a single neural mechanism involving the interaction of the ventral and the dorsal streams with the early visual cortex. The model consists of three representative modules which encode object classes, spatial locations, and elementary features, respectively. These modules are coupled together in a neural dynamical system in the framework of biased competition. The system can be made to operate in either a spatial or an object attention mode by introducing a top-down bias to either the dorsal or the ventral stream modules. In this system, translation invariant object recognition and object spatial localization arise from the interaction among the modules, with the early visual areas playing a key role in mediating such interaction. (C) 2002 Elsevier Science B.V. All rights reserved.