The assignment of syntactic structure and its use to determine propositional aspects of sentence meaning requires the retention of information and computations on that information over short periods of time; i.e., it requires a working memory system. Experimental results in normal subjects and patients with various brain lesions indicate that measurements of working memory that are derived from commonly used tests of this function do not correlate with performance levels on tests of syntactic processing in sentence comprehension. In addition, concurrent verbal memory loads do not affect syntactic processing. These results lead to the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system that is measured by standard working memory tasks and that presumably supports other verbally mediated cognitive functions.

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This investigation explores the contribution of three working memory systems (the phonological loop, the visuo-spatial sketchpad, and the central executive) to the performance differences of sentence comprehension between children with Williams syndrome (WMS) and typically developing children. When 12 children with WMS and 12 typically developing children, matched in the size of acquired lexicon, were tested on a sentence-picture matching test containing nine different sentence types representing different level of syntactic complexity, overall performance of children with WMS was poorer than typically developing children. However, children with WMS showed normal effect of phonological variable as span, and exhibited even better performance than typically developing children on a measure of phonological processing accuracy. On the other hand, children with WMS had reduced visuo-spatial span in the executive system and showed poorer performance than typically developing children on a measure of visuo-spatial accuracy. These findings are argued in terms of the characteristics of language learning of WMS children.

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There has been much controversy concerning the mental mechanisms involved in the processing of complex words, especially between the dual mechanism theory and the single mechanism theory over inflectional morphology. In this article we present a new set of data from Japanese causatives drawn from the experiments on aphasic patients, which show that two different types of causatives may involve two different mechanisms of rule and associative memory, thus demonstrating the validity of the dual mechanism theory over the processes of derivational morphology.

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Eight Japanese children with specific language impairment (SLI), eight age-matched and eight younger children with normal language development were tested with an elicited production task which involved two different kinds of morphologically complex verbs. More specifically, the verbs of focus in this study were lexical inchoatives and lexical causatives, in contrast with syntactic passives and syntactic causatives. As the names indicate, the former two are assumed to be generated within the domain of the lexicon while the latter two are assumed to be generated outside the domain of the lexicon. The obtained data revealed that the children with SLI experienced great difficulty forming the lexicon-external complex verbs, but performed relatively well on the lexicon-internal complex verbs while the performance of the age-matched and younger children with normal language development exhibited no such clear asymmetry. These results suggest that the deficit of SLI severely affects the ability to construct morphological rules that are generated outside the domain of the lexicon whereas their lexical processes remain relatively unaffected.

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This article discusses the issue of initial structure building in sentences processing. To understand a sentence it is necessary to integrate single words into a syntactic structure. I will show how this initial integration might be pursued by the parsing system. The investigation on initial syntactic processing is restricted to limited local relationships such as verb-complement combinations. Taken these relations as an example I will propose that an initial parsing process can be separated into two phases. The first phase uses a general structuring rule (X-bar) to project from a head to a phrase. Thus, it pursues the first integration of a word onto the sentence level by using the category information of the head. This computation is independent from other lexically listed information and frequency considerations. Although these assumptions can be found in the garden-path theory (see Frazier, 1990, for a detailed description) I will point out that the initial processing of a word does not dependent on attachment decisions initiated by other words. The second phase provides information retrieved from a mental lexicon about the subcategorization properties of the complementation. It can be classified as a checking mechanism (Mitchell, 1987) which guarantees the grammatical interpretation of the so far computed structure. As a matter of fact the proposed separation of the initial structure building process into two phases can be seen as a contribution to the discussion of syntactic and lexical computation in sentence comprehension (Frazier & Clifton, 1996; MacDonald, Pearlmutter, & Seidenberg, 1994). Additionally, I will provide experimental evidence for the first and second phase in initial structure building. Furthermore, I claim that both processes are not dependent on each other generally. However, some rare cases exist where the second can influence the first phase. This interaction can occur under restricted circumstances only. All assumptions about processing stages are pursued in a manner which separates syntactic and lexical information use as well as the usage of grammar and mental lexicon. This exploration should be taken as a proposal which needs further evaluation by experimental investigations.

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The purpose of this study is to explore changes of problem solving processes by diagrammatic externalizations. Eighteen undergraduate and graduate students attempted to solve a complicated arithmetic word problem (the 100 yen problem). Fourteen subjects were allowed to write down their own ideas, while other four subjects were prohibited from writing any idea. We stated the differences of their performance and the problem solving processes, comparing both experimental results of the two groups. The results indicated that (1) the subjects improved their performance for solving the 100 yen problem by externalizations, (2) integrating multiple propositions was facilitated by externalizations, (3) externalizing diagrams made the subjects effectively construct propositional networks that were relatively free from specific structures of the given problem.

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