Hemispheric differences in the organization of memory for text ideas.

The goal of this study was to examine hemispheric asymmetries in episodic memory for discourse. Access to previously comprehended information is essential for mapping incoming information to representations of "who did what to whom" in memory. An item-priming-in-recognition paradigm was used to examine differences in how the hemispheres represent discourse. Both hemispheres retained accurate information about concepts from short passages, but the information was organized differently. The left hemisphere was sensitive to the structural relations among concepts in a text, whereas the right hemisphere differentiated information that appeared in one passage from information that appeared in another. Moreover, the right hemisphere, but not the left hemisphere, retained information about the spatial/temporal proximity among concepts in a passage. Implications of these results for the roles of the right and left hemispheres in comprehending connected discourse are discussed.

A memory-retrieval view of discourse representation: The recollection and familiarity of text ideas.

According to most theories of text comprehension, readers construct and store in memory at least two inter-related representations: a text base containing the explicit ideas in a text and a discourse model that contains the overall meaning or "gist" of a text. The authors propose a refinement of this view in which text representations are distinguished by both encoding and retrieval processes. Some encoding processes "unitize" concepts in a text and some "relate" units to one another. Units are retrieved based on familiarity processes in recognition, whereas related units are retrieved based on recollective processes. This distinction was tested in two experiments. In Experiment 1, readers comprehended sentence pairs in which some could be related by means of a causal inference, whereas others were only temporally related. Overall recognition was high in both conditions, but recollection, much more than familiarity, was sensitive to the causal manipulation. In Experiment 2, sentences began with a definite article as a linguistic cue to connect noun phrases or began with an indefinite article. The discourse manipulation had its primary influence on recollection. The authors suggest that the discourse model may be a collection of text ideas that are available to consciousness at retrieval. The gist-level representation of a text may not be a pre-stored structure; rather, it may be generated, in part, as a summary description of recollected text ideas.

Individual Differences in Eye-Movements During Reading: Working Memory and Speed-of-Processing Effects.

Theories of eye-movement control in reading should ultimately describe how differences in knowledge and cognitive abilities affect reading and comprehension. Current mathematical models of eye-movement control do not yet incorporate individual differences as a source of variation in reading, although developmental and group-difference effects have been studied. These models nonetheless provide an excellent foundation for describing and explaining how and why patterns of eye-movements differ across readers (e.g., Rayner, Chace, & Ashby, 2006). Our focus in this article is on two aspects of individual variation: global processing speed (e.g., Salthouse, 1996) and working-memory capacity (e.g., Just & Carpenter, 1992). Using Hierarchical Linear Modeling (HLM) (Raudenbush & Bryk, 2001), we tested the extent to which overall reading speed and working-memory capacity moderate the degree to which syntactic and semantic information affect fixation times. Previous published data (Traxler et al., 2005) showed that working memory capacity and syntactic complexity interacted to determine fixation times in an eye-movement monitoring experiment. In a new set of models based on this same data set, we found that working-memory capacity interacted with sentence-characteristic variables only when processing speed was not included in the model. We interpret these findings with respect to current accounts of sentence processing and suggest how they might be incorporated into eye-movement control models.

The importance of knowledge in vivid text memory: an individual-differences investigation of recollection and familiarity.

The goal of this study was to examine how individual variation in readers' skills and, in particular, their background knowledge about a text are related to text memory. Recollection and familiarity estimates were obtained from remember and know judgments to text ideas. Recollection estimates to old items were predicted by readers' background knowledge, but not by other comprehension-related factors, such as word-decoding skill and working memory capacity. False alarms involving recollection of new items (inferences) were diminished as a function of verbal ability, working memory capacity, and reasoning but increased as a function of background knowledge. The results suggest that recollection indexes the reader's ability to construct a text representation in which text ideas are integrated with relevant domain knowledge. Moreover, these results highlight the importance of background knowledge in explaining individual variation in comprehension and memory for text.