Etiology of Reading Difficulties and Rapid Naming: The Colorado Twin Study of Reading Disability

Children with reading deficits perform more slowly than normally-achieving readers on speed of processing measures, such as rapid naming (RN). Although rapid naming is a well-established correlate of reading performance and both are heritable, few studies have attempted to assess the cause of their covariation. Measures of rapid naming (numbers, colors, objects, and letters subtests), phonological decoding, orthographic choice, and a composite variable (DISCR) derived from the reading recognition, reading comprehension, and spelling subtests of the Peabody Individual Achievement Test were obtained from a total of 550 twin pairs with a positive school history of reading problems. Basic DeFries and Fulker (DF) multiple regression models for the analysis of selected twin data confirmed the heritable nature of phonological decoding, orthographic choice, DISCR, and rapid-naming composites. Bivariate DF models were employed to examine the extent to which deficits in the three reading-related measures covary genetically with rapid naming. Significant bivariate heritability estimates for each of the reading measures with the numbers and letters rapid-naming composite were also obtained. As expected, univariate sib-pair linkage analyses indicated the presence of a quantitative trait locus (QTL) on chromosome 6p21.3 for phonological decoding and orthographic choice deficits. Bivariate linkage analyses were then conducted to test the hypothesis that this QTL for reading difficulties is pleiotropic for slower performance on RN tasks. The results obtained from these analyses did not provide substantial evidence that the 6p QTL for reading difficulties has significant effects on rapid naming; however, larger samples would be required to test this hypothesis more rigorously.     

Reasoning in psychosis: risky but not necessarily hasty

Introduction. A liberal acceptance (LA) threshold for hypotheses has been put forward to explain the well-replicated “jumping to conclusions” (JTC) bias in psychosis, particularly in patients with paranoid symptoms. According to this account, schizophrenia patients rest their decisions on lower subjective probability estimates. The initial formulation of the LA account also predicts an absence of the JTC bias under high task ambiguity (i.e., if more than one response option surpasses the subjective acceptance threshold).

Methods. Schizophrenia patients (n?=?62) with current or former delusions and healthy controls (n?=?30) were compared on six scenarios of a variant of the beads task paradigm. Decision-making was assessed under low and high task ambiguity. Along with decision judgments (optional), participants were required to provide probability estimates for each option in order to determine decision thresholds (i.e., the probability the individual deems sufficient for a decision).

Results. In line with the LA account, schizophrenia patients showed a lowered decision threshold compared to controls (82% vs. 93%) which predicted both more errors and less draws to decisions. Group differences on thresholds were comparable across conditions. At the same time, patients did not show hasty decision-making, reflecting overall lowered probability estimates in patients.

Conclusions. Results confirm core predictions derived from the LA account. Our results may (partly) explain why hasty decision-making is sometimes aggravated and sometimes abolished in psychosis. The proneness to make risky decisions may contribute to the pathogenesis of psychosis. A revised LA account is put forward.     

Naming a giraffe but not an animal: Base-level but not superordinate naming in a patient with impaired semantics

We report data on patient FK, who presented with a marked deficit in accessing semantic knowledge about objects when tested across a range of input and output modalities. FK also showed a high degree of item-specific consistency in object identification, over and above effects due to object familiarity. We show that, despite being better at naming some objects than others, FK was equally poor at discriminating the superordinate categories of the stimuli. Also, he tended to be better at matching nameable items to a base-level label than to a superordinate-level label. We discuss the implications of the data for models of semantic memory.     

Naming a giraffe but not an animal: Base-level but not superordinate naming in a patient with impaired semantics

We report data on patient FK, who presented with a marked deficit in accessing semantic knowledge about objects when tested across a range of input and output modalities. FK also showed a high degree of item-specific consistency in object identification, over and above effects due to object familiarity. We show that, despite being better at naming some objects than others, FK was equally poor at discriminating the superordinate categories of the stimuli. Also, he tended to be better at matching nameable items to a base-level label than to a superordinate-level label. We discuss the implications of the data for models of semantic memory.     

Fronto-central dysfunctions in reading disability depend on subtype: guessers but not spellers

The goal of this study was to test the hypothesis that the inhibitory deficits previously found in children with the guessing subtype of dyslexia (who read fast and inaccurately) can be attributed to dysfunctions in the fronto-central brain areas. For this purpose, the electrocortical correlates of the inhibition mechanism were assessed in a stop task that was adapted for event-related brain potential recording. It was found that in children with the spelling subtype of dyslexia (who read slowly and accurately) and normal readers, a positive component with a fronto-central scalp distribution was related to processes engaged in the inhibition of a response. Guessers did not show this “inhibition P300.” Analyses of the lateralized readiness potential (LRP) data suggested that response inhibition in spellers depended (at least in part) on their ability to inhibit the central activation of the response. In guessers, the association between response inhibition and inhibition of activity in the central motor structures was found to be weaker. It was concluded that the inhibitory deficits in guessers can be attributed to dysfunctions in the fronto-central brain structures involved in selective motor inhibition (indicated by the LRP data) and nonselective motor inhibition (indicated by the P300 data). It was suggested that there may be an association between guessers and attention deficit hyperactivity disorder children in that both clinical groups may suffer from the same type of deficits in executive functioning.     

Programming in asthma: the dice are loaded but not cast

Cite this as: R. J. Hancox and R. Beasley, Clinical & Experimental Allergy, 2010 (40) 1717–1718.     

汉语阅读障碍儿童在快速命名时的眼动特征

目的了解汉语阅读障碍儿童在进行字母、图片快速命名时的眼动特征与规律。方法依ICD-10诊断标准,从儿童发育行为门诊诊断遴选阅读障碍儿童20名,并按年龄、性别、年级匹配20例正常儿童为对照组。对他们进行颜色、数字、字母和图片快速命名测试,记录命名反应时间;采用Eyelink 2 High-Speed Eye Tracker眼动仪记录图片、字母快速命名时的眼动数据,比较两组儿童平均注视时间,平均眼跳幅度,注视次数,眼跳次数的差异。结果SRD组儿童颜色、数字、字母和图片的快速命名时间均长于对照组(44.9±16.1/28.5±3.9,P<0.001;22.3±6.5/16.8±4.3,P=0.001;58.1±32.3/33.1±9.0,P=0.001;54.2±20.4,41.3±7.0,P=0.003)。在字母快速命名中,SRD儿童的平均注视时间延长(342.8±64.2/309.7±42.8,P=0.038),注视次数和眼跳次数增多(126.1±60.1/92.9±21.5;149.4±78.8/95.2±21.5,P=0.011、0.003);在图片快速命名中,SRD儿童的平均眼跳幅度减小(2.9±0.6/3.7±1.0,P=0.10),注视次数和眼跳次数增多(118.0±52.2/98.9±20.3;137.8±58.9/106.9±19.2,P=0.039、0.016)。结论汉语SRD儿童存在快速命名障碍,在快速命名中存在异常的眼动模式,可能反映了其视觉空间和视觉注意缺陷。