Recent Developments in the NL-Soar Garden Path Theory

This report describes a theory of garden path phenomena that is emerging from work on NL-Soar, a computational model of language comprehension embedded within the Soar architecture. The theory is constrained by a corpus of two kinds of sentences: garden paths (GP), which reveal the limitations of human comprehension in dealing with local ambiguities, and non-garden-paths (NGP), which reveal its power in handling local ambiguities. NL-Soar is a single-path comprehender with a limited capacity to repair misanlysed input. A space of repair mechanisms is explored by hand simulation on the corpus. The importance of phonology and plausible search control is established, leading to a theory up to 95% accurate (76% worst case) in predicting performance on 37 distinct GP and NGP types.