Memory and Text Comprehension 577the likelihood of a reader discovering inconsistencies in a
text. In a series of experiments, Carpenter et al. (1994)
demonstrated that reading span accounted for systematic dif-
ferences in the way college students processed text. These
authors argue that individuals with limited working memory
capacity are disproportionately affected by manipulations
that increase the demand on working memory resources dur-
ing comprehension. The decline in performance by low-span
individuals occurs regardless of whether the increase in de-
mand is integrated into the comprehension task (for example,
increasing syntactic complexity or introducing ambiguity
into a text) or represents a demand external to the compre-
hension process (for example, a set of unrelated memory
items).
Regardless of the source of memory demand, it is impor-
tant to note that working memory capacity does not just
affect the amount of information that can be retained during
reading of a text. In fact, many of the systematic comprehen-
sion differences associated with working memory capacity
reflect higher-level processes of text integration and repre-
sentation. For example, Carpenter et al. (1994) found that
high-span readers were more likely to keep multiple repre-
sentations of a homograph active until context could be de-
termined; they also found that high-span readers were better
able to integrate text information that was separated by in-
creasing amounts of intervening text than low-span readers.
Similarly, Whitney, Ritchie, and Clark (1991) found that in-
dividuals with high working memory capacity were better
able to maintain ambiguous interpretations of a text, whereas
low-span individuals were much more likely to choose spe-
cific text interpretations earlier in their reading. Consistent
with all these findings, calculation of the demands a text is
likely to have on working memory has been shown to predict
the actual comprehensibility of the text (Britton & Gulgoz,
1991; J. R. Miller & Kintsch, 1980).
Empirical evidence also ties working memory capacity
directly to comprehension processes. Singer and Ritchot
(1996) found that individuals with high reading spans were
better able to verify bridging inferences about a text. Singer,
Andrusiak, Reisdorf, and Black (1992) found that higher
working memory capacity supported inference processing.
Other studies have confirmed that working memory consis-
tently predicts inference making and text learning (Haenggi &
Perfetti, 1994; Myers, Cook, Kambe, Mason, & O’Brien,
2000). Finally, research has demonstrated that known com-
ponents of working memory can be tied to specific types of
inferential processes. Friedman and Miyake (2000) demon-
strated that maintaining the spatial and causal aspects of a
situation model—a type of cognitive representation of com-
prehended text that is discussed later in this chapter—could
be tied to the visuospatial and verbal components, respec-
tively, of working memory.
The implications of these studies are clear: Working mem-
ory has important and measurable ties to comprehension
processes and, all else remaining equal, individuals with high
working memory capacity are at a comprehension advantage.
However, it should be noted that although working memory
capacity has been shown to have a reliable influence on mea-
sures of inference and learning, other factors can be equally
important in predicting comprehension skills. For example,
domain knowledge can strongly influence the amount of
learning an individual takes from a text; high domain knowl-
edge can compensate for poor decoding skills, low working
memory capacity, very demanding texts, and so on. As we
discuss later in the chapter, many factors can influence the
ultimate comprehension performance of an individual, and
no single factor is sufficient to predict success or failure in
comprehension.Long-Term Working Memory in Discourse
ComprehensionWorking memory, as previously discussed, is our name for
the information that is active and available in consciousness.
Whereas text comprehension clearly depends upon active
processing, storage, and retrieval of information, working
memory is strictly limited in sheer capacity and in the dura-
tion for which items are kept active. Working memory limita-
tions cannot explain empirical evidence that shows capable
readers to be relatively insensitive to interruptions, to be re-
sistant to interference, and to have accurate recall that far
exceeds the capacity of working memory (for a summary, see
W. Kintsch, 1998). Thus, working memory is clearly insuf-
ficient to manage the heavy demands of comprehension. Dis-
course comprehension requires ready access to a large
amount of information, significantly more than laboratory
measurements of the capacity of working memory indicate
is available. Van Dijk and Kintsch (1983, p. 347) list the fol-
lowing memory requirements for discourse comprehension—
information that must be available for analysis and re-
analysis; graphemic and phonological information; words
and phrases, often whole sentences; the propositional struc-
ture of the text, microstructure as well as the macrostructure
(The concepts of text microstructure and macrostructure will
be discussed later in this chapter; for now, consider the
macrostructure to represent the high-level gist of a text and
the microstructure to represent the detailed content of a text.);
the emerging situation model; lexical knowledge and general
world knowledge; and goals, subgoals, and the general task
context. Each of these components of the memory system