Effects of Executive Cognitive Resources on Coherence of Reading Recall for Brief Scientific Texts: an Empirical Investigation

High level reading comprehension is a process that results in a reader’s semantic interpretation of a text, or mental model of that text, referred to as the “reader’s situation model.” Individual differences in readers’ verbal working memory resources, as measured by reading span tasks (RST), and operation span tasks (OST), have shown to influence the construction and coherence quality of the reader’s situation model. Recent theories of semantic reading comprehension suggest that individual differences in other cognitive resources, including cognitive flexibility or “set shifting,” may also influence the construction and coherence quality of readers’ mental representations of texts. This dissertation consists of three experiments and two correlation studies, which examine relationships between college student participants’ non-verbal cognitive flexibility resources, verbal cognitive flexibility resources, verbal working memory resources and prior domain knowledge on the semantic content and semantic coherence of their immediate recall of information contained in brief scientific texts. Experiment 1 showed no main effect of non-verbal cognitive flexibility resources as measured by the standardized WCST, on readers’ recall of total text propositions in a scientific, causally connected text. Further, Experiment 1 showed no main effect of non-verbal cognitive flexibility on readers’ recall of the most salient “coherence relevant” propositions in the scientific, causally connected text. Experiment 2 introduced a new measurement tool for assessing verbal cognitive flexibility resources, referred to as the Verbal WCST. Experiment 2 showed a main effect of verbal cognitive flexibility on readers’ recall of total text propositions of the same scientific text used in Experiment 1. Further, Experiment 2 showed a main effect of verbal cognitive flexibility on readers’ recall of the most salient “coherence relevant” propositions of the same scientific text used in Experiment 1 (Stouffer, Ghiasinejad & Golden, 2014). Experiment 3 was a correlation study that compared one group of participants’ performance on the standardized WCST and their performance on the VWCST. Results of Experiment 3 revealed a moderate positive correlation between the WCST and the VWCST. Experiment 4 examined the effects of individual differences of verbal cognitive flexibility and individual differences of verbal working memory on the immediate recall of brief scientific texts that were intentionally disrupted by information topic shifts. In Experiment 4, verbal cognitive flexibility was operationalized by the VWCST and verbal working memory was operationalized by the Swanson Operation Span Task (OST). Results of Experiment 4 showed a main effect of verbal cognitive flexibility and a main effect of verbal working memory on three dependent variables, which together, measured the quality and quantity of semantic coherence relations in participants’ immediate recall of texts for the reading condition, “High-frequency information topic shifts.” Further, Experiment 4 showed main effects of verbal cognitive flexibility and verbal working memory on the three dependent variables, which measured the quality and quantity of semantic coherence relations in participants’ immediate recall of texts for the reading condition, “Low-frequency information topic shifts.” Experiment 5 was designed to check that the semantic relatedness assumptions of the experimental texts used in Experiment 4 were valid. Results of Experiment 5 demonstrated that participants’ judgments of semantic relatedness between sentence pairs were consistent with experimenters’ judgments of semantic relatedness between sentence pairs. A general discussion follows, which highlights the relationship between the construction of semantic structures in a situation model and “discourse cognitive flexibility” and relationship of verbal cognitive flexibility and verbal working memory to discourse cognitive flexibility in scientific reading comprehension. Evidence for a partial dissociation of working memory and cognitive flexibility, are presented and discussed, in conjunction with results of recent neuroscience research.