Theory-based assessment of acquired dyscalculia.

This article describes a theory-based approach to assessment of acquired dyscalculia. A model of the normal cognitive number-processing/calculation system is presented, and methods are discussed for characterizing number-processing/calculation deficits in terms of functional damage to the mechanisms specified in the model.     

Cognitive representations and processes in arithmetic: inferences from the performance of brain-damaged subjects.

In this article, we present data from two brain-damaged patients with calculation impairments in support of claims about the cognitive mechanisms underlying simple arithmetic performance. We first present a model of the functional architecture of the cognitive calculation system based on previous research. We then elaborate this architecture through detailed examination of the patterns of spared and impaired performance of the two patients. From the patients' performance we make the following theoretical claims: that some arithmetic facts are stored in the form of individual fact representations (e.g., 9 x 4 = 36), whereas other facts are stored in the form of a general rule (e.g., 0 x N = 0); that arithmetic fact retrieval is mediated by abstract internal representations that are independent of the form in which problems are presented or responses are given; that arithmetic facts and calculation procedures are functionally independent; and that calculation algorithms may include special-case procedures that function to increase the speed or efficiency of problem solving. We conclude with a discussion of several more general issues relevant to the reported research.     

Integrated versus modular theories of number skills and acalculia

This paper contrasts two views of the cognitive architecture underlying numerical skills and acalculia. According to the abstract-modular theory (e.g., McCloskey, Caramazza, & Basili, 1985), number processing is comprised of independent comprehension, calculation, and production subsystems that communicate via a single type of abstract quantity code. The alternative, specific-integrated theory (e.g., Campbell & Clark, 1988), proposes that visuospatial, verbal, and other modality-specific number codes are associatively connected as an encoding complex and that different facets of number processing generally involve common, rather than independent, processes. The hypothesis of specific number codes is supported by conceptual inadequacies of abstract codes, format-specific phenomena in calculation, the diversity of acalculias and individual differences in number processing, lateralization issues, and the role of format-specific codes in working memory. The integrated, associative view of number processing is supported by the dependence of modular views on abstract codes and other conceptual inadequacies, evidence for integrated associative networks in calculation tasks, acalculia phenomena, shortcomings in modular architectures for number-processing dissociations, close ties between semantic and verbal aspects of numbers, and continuities between number and nonnumber processing. These numerous logical and empirical considerations challenge the abstract-modular theory and support the encoding-complex view that number processing is effected by integrated associative networks of modality-specific number codes.     

Cognitive mechanisms in numerical processing: evidence from acquired dyscalculia.

This article discusses cognitive neuropsychological research on acquired dyscalculia (i.e., impaired numerical processing resulting from brain damage), surveying issues of current interest, and illustrating the ways in which analyses of acquired deficits can contribute to an understanding of normal processing. I first review the logic whereby inferences concerning normal cognition are drawn from patterns of impaired performance. I then consider research exploring the general functional architecture of the cognitive numerical processing mechanisms, and finally turn to studies aimed at probing the internal structure and functioning of individual processing components.     

Components of quantitative reasoning: General and group ability factors

In this study we tested the hypothesis that quantitative reasoning performance is a function of specific processing components as well as general cognitive abilities such as working memory capacity, reasoning, and verbal comprehension. Subjects were administered tests of these three ability factors as well as tests designed to measure three components thought to underlie algebra word problem solving: problem-type identification, decomposition and sequencing, and problem translation. Confirmatory factor analyses indicated good fits for our models of the general ability factors and the word-problem-solving components. Further analyses indicated that the word-problem-solving components added substantially to the more general cognitive abilities in explaining variance in arithmetic reasoning and math knowledge test scores obtained from the Armed Services Vocational Aptitude Battery. We conclude that although general cognitive ability and/or working memory are certainly important ingredients of quantitative reasoning, specific processing components suggested by cognitive theory are at least as important determinants of performance.     

Basic number processing in children with specific learning disorders: Comorbidity of reading and mathematics disorders

As well as being the hallmark of mathematics disorders, deficits in number processing have also been reported for individuals with reading disorders. The aim of the present study was to investigate separately the components of numerical processing affected in reading and mathematical disorders within the framework of the Triple Code Model. Children with reading disorders (RD), mathematics disorders (MD), comorbid deficits (RD + MD), and typically developing children (TD) were tested on verbal, visual-verbal, and nonverbal number tasks. As expected, children with MD were impaired across a broad range of numerical tasks. In contrast, children with RD were impaired in (visual-)verbal number tasks but showed age-appropriate performance in nonverbal number skills, suggesting their impairments were domain specific and related to their reading difficulties. The comorbid group showed an additive profile of the impairments of the two single-deficit groups. Performance in speeded verbal number tasks was related to rapid automatized naming, a measure of visual-verbal access in the RD but not in the MD group. The results indicate that deficits in number skills are due to different underlying cognitive deficits in children with RD compared to children with MD: a phonological deficit in RD and a deficit in processing numerosities in MD.     

Strategy generalization across orientation tasks: testing a computational cognitive model

Humans use their spatial information processing abilities flexibly to facilitate problem solving and decision making in a variety of tasks. This article explores the question of whether a general strategy can be adapted for performing two different spatial orientation tasks by testing the predictions of a computational cognitive model. Human performance was measured on an orientation task requiring participants to identify the location of a target either on a map (find-on-map) or within an egocentric view of a space (find-in-scene). A general strategy instantiated in a computational cognitive model of the find-on-map task, based on the results from Gunzelmann and Anderson (2006) , was adapted to perform both tasks and used to generate performance predictions for a new study. The qualitative fit of the model to the human data supports the view that participants were able to tailor a general strategy to the requirements of particular spatial tasks. The quantitative differences between the predictions of the model and the performance of human participants in the new experiment expose individual differences in sample populations. The model provides a means of accounting for those differences and a framework for understanding how human spatial abilities are applied to naturalistic spatial tasks that involve reasoning with maps.     

汉语发展性阅读障碍儿童视觉同时性加工技能子成分的发展及其与阅读的关系

通过分别以高频汉字(实验1)和图形非言语材料(实验2)为刺激的两个联合视觉注意任务, 并采用基于Budensen视觉注意理论的参数估计方法, 系统地探查小学三~六年级汉语发展性阅读障碍儿童的视觉同时性加工技能缺陷的内在机制。以43名汉语发展性阅读障碍儿童和46名生理年龄匹配典型发展儿童为被试, 每类被试均被分为小学中年级组(三、四年级)和高年级组(五、六年级)。两个实验均发现不同年级组的阅读障碍儿童在知觉加工速度参数上显著小于控制组儿童。在空间注意分布权重参数上, 实验1的结果显示, 不同于控制组儿童向左侧化发展的注意分布模式, 两个年级组的阅读障碍儿童均表现为无偏的注意分布; 而实验2未发现显著组别差异。且这两种同时性加工子技能分别与不同水平的汉语阅读技能密切相关。结果表明, 汉语阅读障碍儿童在同时加工多个视觉刺激时存在持续的知觉加工速度缓慢的问题, 在同时加工言语类刺激时还表现出异常的空间注意分布模式。本研究有助于从基础认知层面揭示汉语发展性阅读障碍儿童的缺陷机理, 为进一步设计相关的提高阅读效率的干预方案提供理论依据。     

Cardinal limits: Evidence from language awareness and bilingualism for developing concepts of number

The study presented here investigated children's acquisition of cardinality in terms of a framework that isolates two cognitive processing components previously shown to be involved in children's metalinguistic development. These components are called analysis of knowledge and control of processing. In Study 1, children from 3 to 5 years of age were asked to solve three problems that required an understanding of cardinality. The problems were designed to place different demands on these processing components and examine their involvement in specific problems. In Study 2, bilingual children were given two of the problems to compare their performance to a new group of monolinguals. The results from both studies contribute to our knowledge of the development of cardinality by assessing children's ability across several tasks, by classifying those tasks in terms of their reliance on distinct processing components, and by providing a means for relating children's development of number concepts to their development of language. The results also contribute to our knowledge of the cognitive abilities of bilingual children. The implications of these results are that aspects of symbolic development may be a broadly based process that extends beyond domain-specific boundaries.     

Time constraints and resource sharing in adults' working memory spans

This article presents a new model that accounts for working memory spans in adults, the time-based resource-sharing model. The model assumes that both components (i.e., processing and maintenance) of the main working memory tasks require attention and that memory traces decay as soon as attention is switched away. Because memory retrievals are constrained by a central bottleneck and thus totally capture attention, it was predicted that the maintenance of the items to be recalled depends on both the number of memory retrievals required by the intervening treatment and the time allowed to perform them. This number of retrievals:time ratio determines the cognitive load of the processing component. The authors show in 7 experiments that working memory spans vary as a function of this cognitive load.     

Sleep deprivation affects multiple distinct cognitive processes

Sleep deprivation adversely affects the ability to perform cognitive tasks, but theories range from predicting an overall decline in cognitive functioning (because of reduced stability in attentional networks) to claiming specific deficits in executive functions. In the present study, we measured the effects of sleep deprivation on a two-choice numerosity discrimination task. A diffusion model was used to decompose accuracy and response time distributions in order to produce estimates of distinct components of cognitive processing. The model assumes that, over time, noisy evidence from the task stimulus is accumulated to one of two decision criteria and that parameters governing this process can be extracted and interpreted in terms of distinct cognitive processes. The results showed that sleep deprivation affects multiple components of cognitive processing, ranging from stimulus processing to peripheral nondecision processes. Thus, sleep deprivation appears to have wide-ranging effects: Reduced attentional arousal and impaired central processing combine to produce an overall decline in cognitive functioning.     

Number processing and calculation in Brazilian children aged 7-12 years

Numerical cognition is based on two components - number processing and calculation. Its development is influenced by biological, cognitive, educational, and cultural factors. The objectives of the present study were to: i) assess number processing and calculation in Brazilian children aged 7-12 years from public schools using the Zareki-R (Battery of neuropsychological tests for number processing and calculation in children, Revised; von Aster & Dellatolas, 2006) in order to obtain normative data for Portuguese speakers; ii) identify how environment, age, and gender influences the development of these mathematical skills; iii) investigate the construct validity of the Zareki-R by the contrast with the Arithmetic subtest of WISC-III. The sample included 172 children, both genders, divided in two groups: urban (N = 119) and rural (N = 53) assessed by the Zareki-R. Rural children presented lower scores in one aspect of number processing; children aged 7-8 years demonstrated an inferior global score than older; boys presented a superior performance in both number processing and calculation. Construct validity of Zareki-R was demonstrated by high to moderate correlations with Arithmetic subtest of WISC-III. The Zareki-R therefore is a suitable instrument to assess the development of mathematical skills, which is influenced by factors such as environment, age, and gender.     

Liens entre le déclin sensoriel et cognitif dans le vieillissement normal : revue critique de la littérature et apports de l’approche incarnée et située de la cognition

Biological aging impacts many organs including sensory's ones and the brain, and thus, cognition. Research has shown that the sensory and cognitive decline are positively correlated. The main data from this literature are firstly reviewed in the present article. Then, the four main hypotheses that are generally proposed to explain these associations are presented. According to them, sensory decline is supposed to cause cognitive decline, or vice-versa, or these concomitant changes result from the general alteration of the nervous system. However, none of them seems able to account for all of the existing data. Moreover, the precise mechanisms that may drive these associations remain to be clarified. The rest of the article is then dedicated to the embodied and situated cognition approach as it provides a particularly interesting and adequate framework to account for these links. Indeed, according to this approach, cognitive representations are grounded in their sensorimotor properties. In other words, cognitive functioning is not conceived as detached from sensory functioning, but instead directly dependent of it. Representations are thus thought to emerge from the sensorimotor simulation of the properties involved in these representations. Therefore, sensory decline should directly impact cognitive performance. It is then hypothesized that older adults have low-resolution representations decreasing the signal on noise ratio of traces, increasing sensorimotor interferences and thus decreasing cognitive performance. This approach leads to consider low and high levels of sensory and perceptual functioning, which are both impaired in aging. Therefore, the repercussion of the sensory-perceptual decline is not only valid for present processing, but also extend to all past knowledge. Several predictions are then proposed on (1) the link between high-level perceptual functioning and cognitive functioning in older adults; (2) the possible interaction in young adults between sensory and high-level perceptual functioning as a function of the level of interference of the material involved; (3) the possible link between the motor and cognitive functioning in older adults. The clinical consequences in terms of cognitive stimulation of such a perspective will close the article. It is proposed to develop a stimulation program based on pattern separation mechanism to better process sensory interference in order to train older adults to improve cognitive precision and thus performance.     

Speechreading and the Bruce-Young model of face recognition: early findings and recent developments

In the context of face processing, the skill of processing speech from faces (speechreading) occupies a unique cognitive and neuropsychological niche. Neuropsychological dissociations in two cases (Campbell et al., 1986) suggested a very clear pattern: speechreading, but not face recognition, can be impaired by left-hemisphere damage, while face-recognition impairment consequent to right-hemisphere damage leaves speechreading unaffected. However, this story soon proved too simple, while neuroimaging techniques started to reveal further more detailed patterns. These patterns, moreover, were readily accommodated within the Bruce and Young (1986) model. Speechreading requires structural encoding of faces as faces, but further analysis of visible speech is supported by a network comprising several lateral temporal regions and inferior frontal regions. Posterior superior temporal regions play a significant role in speechreading natural speech, including audiovisual binding in hearing people. In deaf people, similar regions and circuits are implicated. While these detailed developments were not predicted by Bruce and Young, nevertheless, their model has stood the test of time, affording a structural framework for exploring speechreading in terms of face processing.     

Neurocognitive correlates of stereotactic thalamotomy and thalamic stimulation in Parkinsonian patients

In the present paper we have reviewed five different studies that relate to neuropsychological consequences of stereotactic thalamotomy and thalamic stimulation in patients with Parkinson's disease. The neuropsychological results are in a strict sense confined to thalamotomy and thalamic stimulation, although the more general message of the importance of investigating cognitive functions before and after surgery applies to other stereotactic techniques for surgical treatment of movement disorders as well. It is argued in the paper that stereotactic thalamotomy provides a unique model for basic research on the neuropsychology of the thalamus, while in return, neuropsychological tests for cognitive dysfunction after surgery may be the most important clinical follow-up. Three general conclusions seem warranted from the data. (1) Parkinsonian patients are impaired on a range of cognitive functions, including language processing, memory, and executive functions. (2) Stereotactic thalamotomy does not further impair the patient; instead, we observed improvement on some tests, particularly verbal memory. (3) In general, there does not seem to be a laterality effect, depending on which side the thalamotomy lesion is applied. An exception to this are dichotically presented simple speech sounds and autonomic responses. In both instances, left-sided brain stimulation produced enhanced performance, while lesioning the left thalamus impaired dichotic listening performance. Finally, we present a new hypothesis for a mechanism behind the thalamotomy effect, based in part on changes in arousal thresholds.     

Strategy choice procedures and the development of multiplication skill

Many intelligent strategy choices may be accomplished through relatively low-level cognitive processes. This article describes a detailed model of how such "mindless" processes might lead to intelligent choices of strategies in one common situation: that in which people need to choose between stating a retrieved answer and using a backup strategy. Several experiments testing the model's applicability to children's single-digit multiplication are reported. These include tests of predictions about when different strategies are used and how early experience shapes later performance. Then, the sufficiency of the model to generate both performance at any one time and changes in performance over time is tested through the medium of a running computer simulation of children's multiplication. The simulation acquires a considerable amount of multiplication knowledge, and its learning and performance parallel those of children in a number of ways. Finally, several implications of the model for understanding cognitive self-regulation and cognitive development are discussed.     

Applying processing trees in social psychology

Processing tree models offer a powerful research framework by which the contributions of cognitive processes to a task can be separated and quantified. The present article reviews a number of applications of processing tree models in the domain of social psychology in order to illustrate the steps to be taken in developing and validating a given model and applying it to the measurement and comparison of processes across experimental and quasi-experimental conditions. Process dissociation models are discussed as special cases of processing tree models. Crucial assumptions of processing tree models are considered and methods to overcome violations of such assumptions are reviewed. In addition to the application of processing tree models for the analysis of social and cognitive processes, their value is also discussed for the elicitation of truthful responses to socially sensitive questions.     

How a Cockpit Remembers Its Speeds

Cognitive science normally takes the individual agent as its unit of analysis. In many human endeavors, however, the outcomes of interest are not determined entirely by the information processing properties of individuals. Nor can they be inferred from the properties of the individual agents, alone, no matter how detailed the knowledge of the properties of those individuals may be. In commercial aviation, for example, the successful completion of a flight is produced by a system that typically includes two or more pilots interacting with each other and with a suite of technological devices. This article presents a theoretical framework that takes a distributed, socio-technical system rather than an individual mind as its primary unit of analysis. This framework is explicitly cognitive in that it is concerned with how information is represented and how representations are transformed and propagated in the performance of tasks. An analysis of a memory task in the cockpit of a commercial airliner shows how the cognitive properties of such distributed systems can differ radically from the cognitive properties of the individuals who inhabit them.     

The impact of cognitive deficits on conflict monitoring. Predictable dissociations between the error-related negativity and N2

Monitoring of ongoing processing plays a critical role in regulating cognitive function. Two event-related potential components, the error-related negativity (ERN) and N2, have been proposed to reflect this monitoring function. Specifically, it has been suggested that both components reflect the role of anterior cingulate cortex (ACC) in monitoring for the occurrence of response conflict. This view appears to be challenged by findings that alcohol consumption and lesions in ACC have dissociable effects on the ERN and N2. Using a computational model, the present research demonstrates that the conflict-monitoring theory can account for these dissociations in terms of the dissociable effects of alcohol and ACC lesions on processing of relevant stimulus information (which determines ERN amplitude) and processing of irrelevant, distracting information (which determines N2 amplitude). The simulation results suggest new interpretations of the cognitive deficits caused by alcohol consumption (impaired stimulus processing) and ACC lesions (impaired attentional control).     

Adaptive executive control: Flexible multiple-task performance without pervasive immutable response-selection bottlenecks

A new theoretical framework, the EPIC (Executive-Process/Interactive-Control) architecture, provides the basis for accurate detailed computational models of human multiple-task performance. Contrary to the traditional response-selection bottleneck hypothesis, EPIC's cognitive processor can select responses and do other procedural operations simultaneously for multiple concurrent tasks. Using this capacity together with flexible executive control of peripheral perceptual-motor components, EPIC computational models account well for various patterns of mean reaction times, systematic individual differences in multiple-task performance, and influences of special training on people's task-coordination strategies. These diverse phenomena, and EPIC's success at modeling them, raise strong doubts about the existence of a pervasive immutable response-selection bottleneck in the human information-processing system. The present research therefore helps further characterize the nature of discrete versus continuous information processing.