Can ACT-R Realize “Newell’s Dream”?

In “The Atomic Components of Thought”, John Anderson and Christian Lebiere claim that ACT-R (4.0) realizes “Newell’s Dream” of a unifying theory of cognition. In this paper it is suggested that each ACT-R model can account for only a finite set of cognitive processes, and cannot therefore be used to model an unbounded whole mind. It is suggested that this is due to an inherent context dependence of ACT-R models. This limitation runs counter to the intuitive criterion that a unifying theory of cognition ought to be able to provide an account of the mind as a system not bound to any particular context. It is suggested that thought in cognitive models ought to be conceived as temporary context specific operations based on persistent context independent knowledge. The basis for a new cognitive architecture, which differentiates thought from knowledge is proposed. This new architecture combines ACT-R with elements of Lawrence Barsalou's situated simulation theory.