Working Memory Capacity in Lexical Disambiguation: An Age Difference Approach

ABSTRACT The present paper, including two experimental studies, explored whether the underlying mechanism of working memory (WM) supporting lexical disambiguation is a general (activation or inhibition) or a specific cognitive resource (involved only in interpretive processes). Regarding general WM resources, we also investigated whether the implied cognitive resources are activating or inhibitory in nature. The aim of the present paper is to test the predictions of the three above mentioned hypotheses in the context of age differences using an experimental paradigm proposed by Miyake, Carpenter, and Just (1994). The obtained results excluded the possibility that there are specific WM resources specifically allocated to lexical disambiguation (considered as an interpretive process). The obtained data confirm the implication of a general activation mechanism, and explain the observed age differences in lexical disambiguation due to the decline of the activation mechanism. However, the nature of this mechanism is still not clear; it can be a general activating attention mechanism of the central executive or a mechanism of short term maintenance (such as phonological buffer processes). KEYWORDS: lexical disambiguation, working memory, cognitive inhibition, aging. INTRODUCTION Literature distinguishes between two types of approaches to written language comprehension: comprehension as the process of meaning construction and comprehension as the process of using constructed meaning (Clark & Clark, 1977). The psycholinguistic mechanisms involved in meaning construction are called interpretive, and usually assessed by on-line measures of language comprehension (for example, eye-tracking techniques or reaction time in semantic priming tasks). Processes involved in using the output of language comprehension are named postinterpretive, and are measured with off-line tasks (for example, correct answers to questions regarding the explicit/implicit contents of a text or recalling the logical units of a paragraph) (Rodd, Gaskell, & Marslen-Wilson, 2002). The concept of lexical access defines the processes that enable the retrieval of a word form from the lexicon on the basis of the available perceptual information (Monsell, Doyle, & Haggard, 1989). During the lexical access the word form and the phonological, semantic, syntactic and thematic information associated to its representation in the mental lexicon are simultaneously activated (Murray & Forster, 2004). According to this approach, lexical access is considered to be a process that contributes to the construction of meaning, thus in terms of the above distinction it is an interpretive psycholinguistic process. In all languages there are words that have two or more meanings and one spelling and pronunciation named homograph (for example, boxer), which explains why written (and more often oral) language is an ambiguous stimulus. Typically one meaning of such a word (the dominant) has a higher frequency in language usage than the other (the subordinate) (Binder & Morris, 1995). In these cases, the construction of meaning involves, beyond the lexical access, a lexical disambiguation phase or in terms of Zwitserlood's (1989) approach, a lexical selection phase. During this second phase, the meaning that fits the actual semantic context is retained. Without exception, all the current models of meaning disambiguation emphasize the importance of the semantic and syntactic context in this process. What distinguishes them is the moment when the contextual information exerts its effect on meaning selection. Based on this criterion we distinguish two types of models of lexical access: the context-dependent lexical access and the contextindependent access (Murray & Forster, 2004). The context-independent access model (Conrad, 1974) assumes a strictly bottom up process, which result in the activation of all meanings of an ambiguous word. …