Working Memory in Language Processing

How is WMC Measured?

To understand language, comprehenders must undertake multiple related processes, including lexical access, syntactic parsing, and contextual integration. As these processes are unfolding, readers must maintain their comprehension goals, information extracted from the text, world knowledge, and the partial products of interpretive processes. Working memory supports each of these functions. Working memory resembles short-term memory, which also keeps information temporarily active. Working memory differs from short-term memory because it entails both storage and processing. Working memory also includes executive processes that regulate and control task-relevant information.

Working memory is uncontroversially a limited capacity system, but different theories make different claims about the factors responsible for capacity [Page 794]limitations. These factors may include limitations on the amount of activation, similarity-based interference, processing speed, encoding and retrieval problems, and the ability to inhibit irrelevant information.

Variation in WMC has been shown to correlate with performance on a range of cognitive tasks, including language comprehension. Complex language-processing tasks place the greatest demands on working memory and so offer the opportunity to observe differences in performance across individuals who differ in WMC. Complex tasks involve multiple component processes, however, which complicates the interpretation of any observed correlations between WMC and task performance.

WMC measures assess an individual's ability to keep information activated while undertaking a task that prevents rehearsal. Reading span is often used to measure WMC. In this task, participants read aloud a set of sentences, presented one at a time. They recall the final word of each sentence after reading the entire set. Reading span is the largest set size for which a reader recalls all the sentence-final words. Reading span correlates with the verbal Scholastic Aptitude Test (SAT) (about .5) and the ability to answer questions about a text (about .8). When reading span and text complexity are used to predict reading times, they interact. Differences between high- and low-capacity comprehenders increase as text complexity increases. However, reading span does not correlate with short-term memory tasks, such as digit span.

...