Computational evidence for the subitizing phenomenon as an emergent property of the human cognitive architecture

A computational modeling approach was used to test one possible explanation for the limited capacity of the subitizing phenomenon. Most existing model s of this phenomenon associate the subitizing span;with an assumed structur al limitation of the human information processing system. In contrast, we s how how this limit might emerge as the combinatorics of the space of enumer ation problems interacts with the human cognitive architecture in the conte xt of an enumeration task. Subitizing-like behavior was generated in two di fferent models of enumeration, one based on the ACT-R cognitive architectur e and the other based on the principles of parallel distributed processing (PDP). Our results provide good qualitative fits to results obtained in a v ariety of empirical studies.