Influence of limiting working memory resources on contextual facilitation in language processing
Stewart, Oliver William Thomas
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Language processing is a complex task requiring the integration of many different streams of information. Theorists have considered that working memory plays an important role in language processing and that a reduction in available working memory resources will reduce the efficacy of the system. In debate, however, is whether or not there exists a single pool of resources from which all language processes draw, or if the resource pool is functionally fractionated into modular subsections (e.g. syntactic processing, lexical processing etc.). This thesis seeks to investigate the role that working memory capacity plays in the utilisation of context to facilitate language processing. We experimentally manipulated the resources available to each participant using a titrated extrinsic memory load (a string of digits the length of which was tailored to each participant). Participants had to maintain the digits in memory while reading target sentences. Using this methodology we conducted six eyetracking experiments to investigate how a reduction of working memory resources influences the use of context in different language processes. Two experiments examined the resolution of syntactic ambiguities (reduced relative clauses); three examined the resolution of lexical ambiguities (balanced homonyms such as appendix); and one explored semantic predictability (It was a windy day so the boy went to the park to fly his… kite). General conclusions are hard to draw in the face of variable findings. All three experiment areas (syntactic, lexical, and semantic) show that memory loads interact with context, but there is little consistency as to where and how this occurs. In the syntactic experiments we see hints towards a general degradation in context use (supporting Single Resource Theories) whereas in the Lexical and Semantic experiments we see mixed support leaning in the direction of Multiple Resource Theories. Additionally, while individual experiments suggest that limiting working memory resources reduces the role that context plays in guiding both syntactic and lexical ambiguity resolution, more sophisticated statistical investigation indicates that these findings are not reliable. Taken together, the findings of all the experiments lead us to tentatively conclude that imposing limitations on working memory resources can influence the use of context in some language processes, but also that that influence is variant, subtle, and hard to statistically detect.