Many explanations of the difficulties associated with interpreting object relative clauses appeal to the demands that object relatives make on working memory. MacDonald and Christiansen (2002) pointed to variations in reading experience as a source of differences, arguing that the unique word order of object relatives makes their processing more difficult and more sensitive to the effects of previous experience than the processing of subject relatives. This hypothesis was tested in a largescale study manipulating reading experiences of adults over several weeks. The group receiving relative clause experience increased reading speeds for object relatives more than for subject relatives, whereas a control experience group did not. The reading time data were compared to performance of a computational model given different amounts of experience. The results support claims for experience-based individual differences and an important role for statistical learning in sentence comprehension processes. George Miller's (1956) landmark description of the nature of short term memory was a characterization of both its limits (7 ± 2 units) and the modulation of these limits through learning, in that the units were chunks, the size of which could change through a person's experience with the material being processed. In discussions of computational capacity since that time, different research paradigms have tended to vary in their attention to the claim of capacity limits vs. the claim that capacity changes through learning. For example, within adult sentence comprehension, many accounts have invoked capacity limits to explain people's difficulties in relative clause comprehension (e.g., Gibson, 1998;Just & Carpenter, 1992;Lewis, Vasishth & VanDyke, 2006). All of these accounts have noted that experience could affect processing abilities, but the focus in these accounts has been on showing how a characterization of capacity limits explains certain aspects of sentence comprehension

The relationship between print exposure and measures of reading skill was examined in college students (N=99, 58 female; mean age=20.3 years). Print exposure was measured with several new self-reports of reading and writing habits, as well as updated versions of the Author Recognition Test and the Magazine Recognition Test (Stanovich & West, 1989). Participants completed a sentence comprehension task with syntactically complex sentences, and reading times and comprehension accuracy were measured. An additional measure of reading skill was provided by participants’ scores on the verbal portions of the ACT, a standardized achievement test. Higher levels of print exposure were associated with higher sentence processing abilities and superior verbal ACT performance. The relative merits of different print exposure assessments are discussed

Verbal working memory (WM) tasks typically involve the language production architecture for recall; however, language production processes have had a minimal role in theorizing about WM. A framework for understanding verbal WM results is presented here. In this framework, domainspecific mechanisms for serial ordering in verbal WM are provided by the language production architecture, in which positional, lexical, and phonological similarity constraints are highly similar to those identified in the WM literature. These behavioral similarities are paralleled in computational modeling of serial ordering in both fields. The role of long-term learning in serial ordering performance is emphasized, in contrast to some models of verbal WM. Classic WM findings are discussed in terms of the language production architecture. The integration of principles from both fields illuminates the maintenance and ordering mechanisms for verbal information.Keywords working memory; language production; phonological encoding; serial ordering; speech errors Nearly 30 years ago, Albert Ellis (1980) observed that errors on tests of verbal working memory (WM) paralleled those that occur naturally in speech production. Despite this significant observation, the majority of memory and language research since that time has focused on relations between verbal WM and language comprehension and acquisition rather than on the relation between verbal WM and language production (Baddeley, Eldridge, & Lewis, 1981;Caplan & Waters, 1999;Daneman & Carpenter, 1980, 1983Engle, Cantor, & Carullo, 1992;Gathercole & Baddeley, 1990;Just & Carpenter, 1992). The relative inattention to language production is striking given the production demands of typical verbal WM tasks: the maintenance and sequential output of verbal information. In this review, we examine the relation between verbal WM and language production processes in light of new behavioral and theoretical advances since Ellis's initial observations.Verbal WM refers to the temporary maintenance and manipulation of verbal information (Baddeley, 1986). In exploring the production-WM relation, our review emphasizes domain-specific (i.e., verbal) maintenance processes in WM rather than the domain-general, attentional processes that are hypothesized to oversee processing across different domains (e.g., verbal, visual;Baddeley, 1986;Cowan, 1995). Obviously, language production processes must be involved during output in spoken recall, but the hypothesis that we explore here is that the production system is crucial to maintenance as well. We suggest that the domain-specific mechanism underlying the maintenance of serial order in verbal WM is achieved by the language production architecture rather than by a system specifically dedicated to short-term maintenance.Language production planning naturally involves the maintenance and ordering of linguistic information. This information ranges over multiple levels, including messages (several different points that the speaker plans to make), words within phras...

Abstract■ Verbal working memory ( VWM), the ability to maintain and manipulate representations of speech sounds over short periods, is held by some influential models to be independent from the systems responsible for language production and comprehension [e.g., Baddeley, A. D. Working memory, thought, and action. New York, NY: Oxford University Press, 2007]. We explore the alternative hypothesis that maintenance in VWM is subserved by temporary activation of the language production system [Acheson, D. J., & MacDonald, M. C. Verbal working memory and language production: Common approaches to the serial ordering of verbal information. Psychological Bulletin, 135, 50-68, 2009b]. Specifically, we hypothesized that for stimuli lacking a semantic representation (e.g., nonwords such as mun), maintenance in VWM can be achieved by cycling information back and forth between the stages of phonological encoding and articulatory planning. First, fMRI was used to identify regions associated with two different stages of language production planning: the posterior superior temporal gyrus (pSTG) for phonological encoding (critical for VWM of nonwords) and the middle temporal gyrus (MTG) for lexical-semantic retrieval (not critical for VWM of nonwords). Next, in the same subjects, these regions were targeted with repetitive transcranial magnetic stimulation (rTMS) during language production and VWM task performance. Results showed that rTMS to the pSTG, but not the MTG, increased error rates on paced reading (a language production task) and on delayed serial recall of nonwords (a test of VWM). Performance on a lexical-semantic retrieval task (picture naming), in contrast, was significantly sensitive to rTMS of the MTG. Because rTMS was guided by language production-related activity, these results provide the first causal evidence that maintenance in VWM directly depends on the long-term representations and processes used in speech production. ■

Abstract■ The posterior middle temporal gyrus (MTG) and inferior frontal gyrus (IFG) are two critical nodes of the brainʼs language network. Previous neuroimaging evidence has supported a dissociation in language comprehension in which parts of the MTG are involved in the retrieval of lexical syntactic information and the IFG in unification operations that maintain, select, and integrate multiple sources of information over time. In the present investigation, we tested for causal evidence of this dissociation by modulating activity in IFG and MTG using an offline TMS procedure: continuous theta-burst stimulation. Lexical-syntactic retrieval was manipulated by using sentences with and without a temporarily word-class (noun/verb) ambiguity (e.g., run). In one group of participants, TMS was applied to the IFG and MTG, and in a control group, no TMS was applied. Eye movements were recorded and quantified at two critical sentence regions: a temporarily ambiguous region and a disambiguating region. Results show that stimulation of the IFG led to a modulation of the ambiguity effect (ambiguous-unambiguous) at the disambiguating sentence region in three measures: first fixation durations, total reading times, and regressive eye movements into the region. Both IFG and MTG stimulation modulated the ambiguity effect for total reading times in the temporarily ambiguous sentence region relative to the control group. The current results demonstrate that an offline repetitive TMS protocol can have influences at a different point in time during online processing and provide causal evidence for IFG involvement in unification operations during sentence comprehension. ■