Left-Corner Parsing With Distributed Associative Memory Produces Surprisal and Locality Effects

This article describes a left-corner parser implemented within a cognitively and neurologically motivated distributed model of memory. This parser's approach to syntactic ambiguity points toward a tidy account both of surprisal effects and of locality effects, such as the parsing breakdowns caused by center embedding. The model provides an algorithmic-level (Marr, 1982) account of these breakdowns: The structure of the parser's memory and the nature of incremental parsing produce a smooth degradation of processing accuracy for longer center embeddings, and a steeper degradation when they are nested, in line with recall observations by Miller and Isard (1964) and speed-accuracy trade-off observations by McElree et al. (2003). Modeling results show that this effect is distinct from the effects of ambiguity and exceeds the effect of mere sentence length.