Memory structures that subserve sentence comprehension

Measures of the speed and accuracy of processing sentences with nonadjacent dependencies derived from the response-signal speed-accuracy tradeoff procedure were used to examine the nature of the memory system that underlies sentence comprehension. Three experiments with different sentence structures demonstrated that the accuracy of processing a dependency decreased as more material was interpolated between nonadjacent constituents. However, processing speed was unaffected by the amount of interpolated material, indicating that memory representations for previously processed constituents can be accessed directly. These results suggest that a content-addressable memory system mediates sentence comprehension, in which syntactic and semantic information provide direct access to memory representations without the need to search through extraneous representations. Notably, content-addressability appears to underlie the interpretation of sentence structures that also require the recovery of order information, a type of operation that has been shown to necessitate a slow search process in list-learning experiments (McElree, 2001; McElree & Dosher, 1993).