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Studies of subtypes of DSM-IV attention-deficit/hyperactivity disorder (ADHD) have provided inconsistent support for the discriminant validity of the combined type (ADHD-C) and predominantly inattentive type (ADHD-I). A large sample of children and adolescents with ADHD (N = 410) and a comparison group without ADHD (N = 311) were used to test the internal and external validity of sluggish cognitive tempo (SCT), a dimension characterized by low energy and sleepy and sluggish behavior. SCT scores were then incorporated in analyses of ADHD subtypes to test whether the discriminant validity of ADHD-C and ADHD-Icould be improved by includingSCT symptoms as part of the criteria for ADHD-I. Factor analyses of parent and teacher ratings indicated that six SCT items loaded on a factor separate from symptoms of ADHD and other psychopathology, providing important support for the internal validity of SCT. The external validity of SCT was supported by significant associationsbetween SCT and measures of functional impairment and neuropsychological functioning when symptoms of ADHD and other psychopathology were controlled. However, contrary to initial predictions, high levels of SCT did not identify a subgroup of ADHD-I that was clearly distinct from ADHD-C. Instead, the current results suggest that DSM-IV inattention and SCT are separate but correlated symptom dimensions that are each independently associated with important aspects of functional impairment and neuropsychological functioning.

The present study explored whether different executive control and speed measures (working memory, inhibition, processing speed, and naming speed) independently predict individual differences in word reading and reading comprehension. Although previous studies suggest these cognitive constructs are important for reading, we analyze the constructs simultaneously to test whether each is a unique predictor. We used latent variables from 483 participants (ages 8 to 16) to portion each cognitive and reading construct into its unique and shared variance. In these models we address two specific issues: (a) given that our wide age range may span the theoretical transition from “learning to read” to “reading to learn,” we first test whether the relation between word reading and reading comprehension is stable across two age groups (ages 8 to 10 and 11 to 16); and (b) the main theoretical question of interest: whether what is shared and what is separable for word reading and reading comprehension are associated with individual differences in working memory, inhibition, and measures of processing and naming speed. The results indicated that: (a) the relation between word reading and reading comprehension is largely invariant across the age groups; (b) working memory and general processing speed, but not inhibition or the speeded naming of non-alphanumeric stimuli, are unique predictors of both word reading and comprehension, with working memory equally important for both reading abilities and processing speed more important for word reading. These results have implications for understanding why reading comprehension and word reading are highly correlated yet separable.

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The effect of a reading perspective on online text processing was studied by recording readers' eye movements during reading. Participants read an expository text about 4 countries with the goal of deciding whether one of the countries, designated by the experimenter as the reading perspective, would be a good new place of residence. The results showed better memory for perspective-relevant information and longer fixation times on perspective-relevant information. Individual differences in working memory were assessed with the reading span test. Results showed that the time course of the perspective effect varied with memory span: High-span readers showed a perspective relevance effect on initial reading of the target segments, whereas low-span readers showed the effect only in the later look backs.Usually, when reading expository text, one is reading not just for the fun of it but for a specific purpose; for example, to find information regarding a question in which one is interested. In other words, one adopts a specific reading perspective from which one reads the text at hand. The purpose of this study was to examine how the perspective adopted by the reader influences the processing of expository text.In this study, participants read an expository text that described four remote countries: Andorra, Anguilla, Pitcairn, and Honduras. Before reading, the participants were instructed to adopt a reading perspective. One half of the participants DISCOURSE PROCESSES, 33(2),[159][160][161][162][163][164][165][166][167][168][169][170][171][172][173]