Executive processing in learning-disabled readers

Three experiments determine whether memory difficulties experienced by learning-disabled readers may be attributable, in part, to executive processing. In Experiment 1, learning-disabled readers, matched to skilled readers on chronological age and reading-comprehension ability, were compared on the Concurrent Digit Span measure presented under high (6-digit) and low (3-digit) memory-load conditions as they concurrently sorted cards into verbal or nonverbal categories. Experiment 2 utilized the same task as Experiment 1, except that learning-disabled (LD) readers of low and average working-memory capacity were compared with skilled readers of average and high working-memory capacity. Both experiments clearly showed that LD readers' performance is depressed under high memory-load conditions. Experiment 2 also indicated that overall performance of non-learning-disabled (NLD) readers was predictable from LD readers, suggesting that ability-group differences are related to global processing efficiency rather than to isolated verbal and nonverbal systems. In Experiment 3, LD and NLD readers were compared on their ability to recall central and secondary information from base and elaborative sentences tasks under high- and low-effort encoding conditions. LD readers had significantly poorer secondary recall during high-effort encoding conditions when compared to skilled readers. Taken together, the results are discussed within a framework that views individual differences in reading comprehension as reflecting, in part, executive processing (i.e., resource monitoring) activities.     

Learning disabilities, distinctive encoding, and hemispheric resources

The purpose of this study was to isolate possible sources of learning ability differences in distinctive encoding of item-specific and relational information. Two mechanisms postulated as underlying ability group differences were attentional capacity (as inferred from the magnitude and direction of correlations between primary and secondary recall) and resource monitoring strategies (as reflected in measures of selective attention and laterality). In Experiment 1, learning disabled and nondisabled childrens' word recall was compared on dichotic listening recall tasks that included nonorienting instructions, and orienting instructions that directed children's attention toward semantic, phonemic, or structural word features. Disabled children showed lower recall and more diffuse selective attention to word features than nondisabled children. Reciprocity (negative correlations) between targeted and background words within and between ability groups was comparable, except when targeted word features were phonemically organized. Experiment 2 indicated that disabled childrens' cued recall was inferior to that of nondisabled children, even though both ability groups produced comparable symmetrical recall patterns related to ear presentations. Taken together, the results suggest that the locus of disabled childrens' distinctive encoding deficiencies is related to resource monitoring strategies during interhemispheric processing.     

A developmental study of learning disabilities and memory

Seven-, ten-, and thirteen-year-old learning-disabled (LD) and non-learning-disabled (NORM) children were presented specially structured lists of 38 words each and tested for free recall. Each list contained only four semantically related words. Two of the four related words were presented contiguously (serial positions 9 and 10) and the other two words were spaced (serial positions 20 and 30). All children recalled disproportionately more adjacent words (item 9 or 10) than any other words. Spaced words (items 20 and 30) were less likely to be recalled by the younger children than by the older children and by the LDs than by the NORMS. These findings provided support for the distinction between automatic and purposive semantic processing. NORMs' recall was governed by purposive semantic processing to a greater extent than was LDs' recall. However, no group or age differences were observed in automatic semantic processing.     

Memory, acquisition, and category clustering in learning-disabled children.

In Experiment 1, single trial, immediate-free recall of learning disabled and nondisabled children was compared. The primacy effect in learning-disabled children was lower, suggesting that rehearsal or other types of elaborative encoding may be deficient in these children. In Experiment 2, acquisition of randomly presented categorical lists in a multitrial-free recall task was compared in learning disabled and nondisabled children. One-half of each group was required to learn the same number of words (34 per list), whereas list length for the other half exceeded the primacy effect of each child in immediate-free recall to the same degree. When the same number of items was learned, acquisition was slower in learning disabled than nondisabled children. When the number of items varied according to the primacy effect of each child, acquisition of both groups was similar. Clustering was lower in learning disabled than nondisabled children. In Experiment 3, multitrial-free recall acquisition of categorical lists was examined in a subject-paced task. When the number of words learned exceeded the primacy effect of each child to the same degree, trials to criterion were similar in both groups but, when the children learned the same number of items, learning-disabled children required more trials to criterion. Presentation rates were faster in learning-disabled children. Presentation rates were negatively correlated with trials to criterion and positively correlated with clustering and primacy in immediate-free recall, suggesting that study time may be taken up by clustering, rehearsal, and/or other encoding strategies. Deficient elaborative encoding may be responsible for the slower acquisition of learning-disabled children.     

Executive processing in free recall of categorized lists

The present study examines the cognitive processes that operate in free recall of categorized lists by manipulating semantic structure of the lists and using a dual task methodology to restrict the processes that make demands on limited-capacity resources, the central executive resources. Relying on the assumption that, in free recall of categorized lists, the search for category names is a strategic controlled process that demands executive resources, lists with different numbers of categories ranging from 2 to 6 were employed. The results showed an effect of a secondary task on retrieval in the 4- and the 6-category list conditions, but not in the 2-category list condition. In contrast to retrieval, the secondary task interference at encoding produced an effect on recall of all three types of lists. An interesting finding was that an effect on clustering was found only when interference was present at encoding, not when it was at retrieval. This finding was in line with the suggestion (Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998) that switching (shifting between different category items) rather than clustering is related to executive functioning, and suggested that clustering may be a measure of two different types of processing: (1) executive processing at encoding and (2) automatic processing at retrieval. In addition, a different pattern of results was obtained when low frequency category words were used, indicating that the frequency of category words is an important determinant in free recall of categorized lists. Overall, the present results support the two-process account of retrieval of category words (Rosen & Engle, 1997) and the view that there are fundamental differences between encoding and retrieval processes (Naveh-Benjamin, Craik, Guez, & Dori, 1998; Naveh-Benjamin & Guez, 2000).     

Item-cued directed forgetting of related words and pictures in children and adults: selective rehearsal versus cognitive inhibition

The main purpose of this study was to compare the relative importance of selective rehearsal and cognitive inhibition in accounting for developmental changes in the directed-forgetting paradigm developed by R. A. Bjork (1972). In two experiments, children in Grades 2 and 5 and college students were asked to remember some words or pictures and to forget others when items were categorically related. Their memory for both items and the associated remember or forget cues was then tested with recall and recognition. Fifth graders recognized more of the forget-cued words than college students did. The pattern of results suggested that age differences in rehearsal and source monitoring (i.e., remembering whether a word had been cued remember or forget) were better explanatory mechanisms for children's forgetting inefficiencies than retrieval inhibition was. The results are discussed in terms of a multiple process view of inhibition.     

Visual and auditory selective attention and reflection-impulsivity in normal and learning-disabled boys at two age levels

Selective attention to visual and auditory stimuli and reflection-impulsivity were studied in normal and learning-disabled 8- and 12-year-old boys. Multivariate analyses, followed by univariate and paired-comparison tests, indicated that the normal children increased in selective attention efficiency with age to both visual and auditory stimuli. Learning-disabled children increased in selective attention efficiency with age to auditory, but not to visual, stimuli. Both groups increased with age in reflection as measured by Kagan's Matching Familiar Figures Test (MFF). The 8-year-old learning-disabled children were more impulsive than the 8-year-old normals on MFF error scores, but not on MFF latency scores. No difference occurred between the 12-year-old learning-disabled and normal children on either MFF error or MFF latency scores. Correlations between the selective attention scores and MFF error and latency scores were not significant.This research was supported in part by BEH grant G007507227. The authors are indebted to Eleanor McCandless for her assistance in securing the learning-disabled subjects and to James McLeskey and Michael Popkin for their assistance in collecting and analyzing data.     

Development of the false-memory illusion

The counterintuitive developmental trend in the Deese-Roediger-McDermott (DRM) illusion (that false-memory responses increase with age) was investigated in learning-disabled and nondisabled children from the 6- to 14-year-old age range. Fuzzy-trace theory predicts that because there are qualitative differences in how younger versus older children and disabled versus nondisabled children connect meaning information across the words on DRM lists, certain key effects that are observed in adult studies will be absent in young children and in learning-disabled children. Data on 6 such adult effects (list strength, recall inflation, delayed inflation, delayed stability, thematic intrusion, and true-false dissociation) were used to investigate this hypothesis, and the resulting data were consistent with prediction.     

Executive Function and Processing Resources as Predictors of Adult Age Differences in the Implementation of Encoding Strategies

This research examined adult age differences in recall of word lists under different encoding conditions: association (story generation), rehearsal, and a control condition. Executive function and cognitive processing resources (speed and working memory) were investigated as mediators of these age differences. Younger (aged 17-48 years) and older (aged 65-88 years) adults completed a battery of tests of executive function, speed of information processing, working memory, and recall. Age differences in recall were evident for those who used the complex association encoding strategy only. For those using the association strategy, an examination of encoding strategy protocols revealed age differences in the integration of words, which were also related to subsequent recall performance. The association between integration and recall was accounted for by executive function and working memory, but not by speed of processing. Speed accounted for age differences in recall but its contribution to recall was largely independent from that of the impact of integration during encoding.     

Inhibitory processes, working memory, phonological awareness, naming speed, and early arithmetic achievement

This study identified the cognitive processes that underlie the individual differences in early mathematical performance in elementary school children. Taking into account the Baddeley framework multicomponent model, the inhibitory processes, working memory, phonological awareness, and naming speed are considered to be related to early math learning. To examine this relationship, we compared the performance of a total of 424 typically developing middle-class children, aged between 4 and 7 years in a battery of cognitive and early numeric tests: The Utrecht Early Numeracy Test, the Rapid Automatized Naming Test, Spanish version of the Stroop task, the Numeracy Interference Test, Digit Span test, and Phonological Knowledge Test. The mean age of the participants was 72.21 months (sd = 14.8), and 48.6% were male and 51.4% were female. The results demonstrated that children performing worst on central executive, phonological processing, and inhibitory processes showed lower results in early mathematical tasks measured by The Utrecht Early Numeracy Test. Results supported the notion that the executive system is an important predictor of children's mathematical performance.     

Information processing and speech lateralization in learning-disabled children

The relationship between information processing and speech lateralization was investigated in learning-disabled children. The Kaufman Assessment Battery for Children (K-ABC) assessed simultaneous and successive processing while a dichotic listening paradigm with free recall and directed attention conditions assessed speech lateralization. A three-factor ANOVA design conducted on the dichotic data revealed that normal children demonstrated stronger right ear advantage (REA); whereas learning-disabled showed weaker right ear advantage. Further, lambda analyses conducted on individual subjects revealed that the learning-disabled did not demonstrate the REA, were not biased attenders, and did not get more right ear than left ear items when attention was directed to one ear. Multiple-regression analysis was used to predict sequential processing from the dichotic data for both groups. Learning-disabled children demonstrated a substantial deficit in sequential processing as compared to normal children. These results indicate that learning-disabled children may not have adequate cerebral lateralization of receptive speech processes, shift their attention more readily, and are more inadequate in sequential processing that presumably subserves language functioning. Perhaps learning-disabled children have deficiencies of processor capacity of salient areas of the left (language) hemisphere.     

Working memory contributions to reading comprehension components in middle childhood children

This study examined working memory contributions to reading comprehension subskills in Greek children (mean age 9 years, 1 month). The phonological loop of the Baddeley and Hitch working memory model was assessed with 3 recall tasks (words, nonwords, and digits) and a word list matching task. The central executive (CE) was assessed with 3 tasks (listening, counting, and backward digit recall). Participants were also given a receptive vocabulary task, a reading fluency task, and written stories accompanied by comprehension questions. Canonical correlation analyses showed that the comprehension variables were related to the CE rather than the phonological loop measures. CE functions were more strongly associated with elaborative inference generation (involving significant offline processing) and comprehension control (involving metacognitive monitoring). Smaller yet significant associations were observed between the CE and the necessary inference and literal comprehension measures, whereas a moderate relationship was found in the case of the simile comprehension variable. Among the CE variables, listening recall demonstrated the highest loading on the canonical function, followed by moderate yet significant counting and backward digit recall loadings. Vocabulary was found to fully mediate several associations between working memory and comprehension measures; however, the relationship between listening recall and elaborative inferences was partly mediated. Reading fluency and, on several occasions, Greek vocabulary knowledge did not mediate the relationships between CE measures and comprehension skills assessed. This study demonstrates the usefulness of CE measures for identifying young children's possible difficulties in carrying out specific reading comprehension processes.     

The effect of increased incentive on free recall by learning-disabled and nondisabled children

Immediate free recall by learning-disabled and nondisabled children was compared under two incentive conditions. Recall of the first few words of each list by disabled children and younger nondisabled children was lower than that by older nondisabled children, and receiving a monetary reward increased early list item recall by older disabled and nondisabled learners. These findings suggest that elaborative encoding processes, such as rehearsal, are impaired in younger disabled and nondisabled children and that receiving a reward increased elaborative encoding by older children. Similar recall of the last few list items by all groups suggests that attention and immediate memory are comparable in disabled and nondisabled children of different ages. Receiving a reward increased recall of the last few list items by younger disabled and nondisabled children, suggesting that a reward increased attention, immediate memory, or both, in these groups. Because receiving a reward increased recall equally in all groups, lower motivation did not appear to be responsible for the lower recall by younger nondisabled children and learning-disabled children.     

Negative air ionization improves memory and attention in learning-disabled and mentally retarded children

The effect of increased concentrations of ambient negative air ions on incidental visual memory for words and purposive auditory memory for dichotic digits was investigated in 20 normal grade 4 children, 8 learning-disabled children, and 8 mildly mentally retarded children. Half in each group were assigned randomly to an unmodified air-placebo condition under double-blind testing procedures. All of the children breathing negatively ionized air were superior in incidental memory. In dichotic listening, the negative ions produced a counter-priming effect in the two learning-impaired groups, offsetting the difficulties that they showed under placebo in switching attention selectively from one ear to the other. The action of negative ions on the neurotransmitter, serotonin, may be the mechanism by which negative ions produce such behavioral effects. In view of the important environmental and remedial implications of these novel findings, interpretations should be made cautiously pending larger scale replications.This research was supported by a grant from the Ontario Institute for Studies in Education. We wish to thank Paul Hunnisett, who was the first person to our knowledge to suggest that negative ions may have an effect on children's behavior. We also thank Dave Patterson, superintendent of Special Services with the Northumberland and Newcastle Board of Education, for supporting this study, and Muriel Fung, OISE, for assistance with the data analysis.     

Evidence for language recoding in autistic, retarded and normal children: a re-examination

In a replication and extension of earlier studies by Hermelin & O'Connor, language recoding abilities in autistic, retarded and normal children matched for mental age and digit span, were compared in a verbal recall task. Random word lists, sentences, and anomalous sentences, eight or 12 items in length (for high and low memory span subgroups) were presented and the number of words recalled from each type of input was scored. All low span children recalled sentences better than random lists with normal children superior to retarded and autistic children and the latter group poorer than the retarded group. Autistic children showed a recency effect with both types of input. There were no group differences amongst high span children and sentences were again better recalled than random lists. In Expt II sentences were better recalled than anomalous sentences, with autistic and retarded children equivalent in performance and poorer than normal children. Although low span autistic children were clearly deficient in recall of sentence material when compared with the two control groups, the effect of conditions showed that they were able to use structure to improve recall. Since high span autistic children did not perform differently from controls it is suggested that results from this kind of study may not be generalizable, and that claims for a specific coding deficit in autistic children need further substantiation.     

Working memory in skilled and less skilled readers

This study assessed skilled and less skilled readers' working memory performance. Fifty skilled and less skilled readers at two age levels were presented with sentence span and concurrent memory tasks. The span task results indicated that working memory differences exist between reading groups. The concurrent task revealed performance deficits for less skilled readers across verbal and nonverbal conditions, suggesting a central processing deficiency. Age differences were isolated to skilled readers. It was concluded that less skilled readers' working memory deficiencies were pervasive in the sense that they involve deficiencies in memory components related to central executive processing.The authors are indebted to the University Laboratory School, University of Northern Colorado, and Greeley School District 6 for providing subjects for this study. Special appreciation is given to Dr. Neil Henderson, Sue Swaim, and Karen Cash for their administrative assistance. This study was supported by a grant from the U. S. Office of Special Education and Rehabilitative Services to the first author.     

Cognitive processes that underlie mathematical precociousness in young children

The working memory (WM) processes that underlie young children's (ages 6-8 years) mathematical precociousness were examined. A battery of tests that assessed components of WM (phonological loop, visual-spatial sketch pad, and central executive), naming speed, random generation, and fluency was administered to mathematically precocious and average-achieving children. The results showed that (a) precocious children performed better on executive processing, inhibition, and naming speed tasks than did average-achieving children, although the two groups were statistically comparable on measures of the phonological loop and visual-spatial sketch pad, and (b) the executive component of WM predicted mathematical accuracy independent of chronological age, reading, inhibition, and naming speed. The results support the notion that the executive system is an important predictor of children's mathematical precociousness and that this system can operate independent of individual differences in the phonological loop, inhibition, and reading in predicting mathematical accuracy.     

High and low gender schematic children's release from proactive interference

Thirty-seven 4–5 year-old predominantly white children from moderate SES households, identified as high and low gender schematic, completed a Release from Proactive Interference task (RPI) comprised of drawings of same-sex gender-typed toys and animals. The RPI task assesses spontaneous comprehension, encoding, and short-term recall of items from two categories of information. As predicted, high gender schematic children demonstrated significantly greater patterns of release from proactive interference than low schematic children. Specifically, high and low schematic children's patterns of recall following a shift from same-sex gender-typed toys to animals differed significantly, suggesting that gender roles are a more salient and influential information processing dimension to high than low gender schematic children. Results add to data validating the present measure of gender schematicity and its ability to differentiate individual differences in the salience of gender roles to young children. Results also corroborate and expand on theory and research describing the impact and consequences of individual differences in the salience of the gender role dimension on the information processing of high and low gender schematic children.Completion of this project was facilitated, in part, by an Academic Challenge Award from the University of Toledo. This support is gratefully acknowledged. Special thanks to Narina Nightingale for her comments and suggestions on earlier drafts of this article, and to Stephanie Sellers at the University of Toledo, and to Ashley Lyster at the University of Wyoming for their data collection efforts and to the faculty, children, and parents of the Loving Tree Preschool and the Gateway School, both of Toledo, Ohio, and the University of Wyoming Child Care Center, and especially to Director Mark Bittner for his assistance with this research. A shorter version of this article was presented at the annual meetings of the Western Psychological Association, Phoenix, Arizona, April 1993.To whom reprint requests should be addressed at Department of Psychology, University of Wyoming, P. O. Box 3415, Room 135 Biological Sciences Bldg, Laramie, WY 82071-3415.     

语文学习困难儿童的工作记忆与加工速度

加工速度和工作记忆反应了不同的认知加工过程,在认知发展研究中,加工速度和工作记忆所起的作用仍存在较大的分歧.采用多因素混合实验设计,在严格控制条件下,比较了语文学习困难和控制组儿童的工作记忆和加工速度.结果发现,与控制组相比,语文学习困难儿童在工作记忆和加工速度方面均存在明显的不足,但加工速度不能解释不同能力组之间的差异,语文学习困难儿童的缺陷在于工作记忆能力的下降.工作记忆的缺陷在于言语工作记忆和中央执行功能的不足,与视空间工作记忆能力无关.语文学习困难既存在一般的工作记忆缺陷(中央执行功能)也存在特定的工作记忆(言语工作记忆)能力的不足.     

Negatively biased recall in children with self-reported symptoms of depression

This study investigated differences in depressed and nondepressed children's recall of positively and negatively reinforced behavior. Twenty-six children with self-reported symptoms of depression in the fourth through sixth grades were compared with a matched sample of 26 nondepressed children to determine if there was a negative bias in depressed children's recall. Subjects first generated guesses of the most common associations to each of a series of 40 words. Later, when compared with their nondepressed peers, the children with depressive symptomology were less accurate in recalling which words they had answered correctly and remembered fewer of their own correct responses. They also did more poorly when asked to recall the correct answers that had been provided by the investigator. The two groups did not differ, however, in their recall of which items had been answered incorrectly or in their recall of their previous wrong responses. These results suggest that children with self-reported depressive symptomology do not remember negative experiences more than do nondepressed children; rather, they recall positive experiences less well. Selective forgetting of positively reinforced behavior could be a serious handicap for depressed children in school. It could also play an important role in the maintenance and perhaps even the etiology of depressive symptomatology in children.We wish to thank Bruce Compas for his helpful comments on an earlier draft of this paper.