1,721,004 research outputs found
Typical and Atypical Development of Numerical Representation
Full text linkHow numerical information is represented? Recent studies have highlighted the prominent role of preverbal core knowledge systems for representing numerical quantities: the Object Tracking System (OTS) and the Approximate Number System (ANS; or analogue magnitude system). The former is general mechanism which allows individuals to track the spatio-temporal characteristics of the objects and its capacity is limited (3-4 items). The latter is a quantitative mechanism which entails the representation of each numerosity as a distribution of activation on the mental number line. In the present work we investigated several aspects of these two systems along with numerical and non-numerical estimation ability in typical and atypical development.
In Study 1.1, we implemented an imitation task to investigate the spontaneous focusing on numerosity in 2 ½ year-old children. The results suggest that most of the children employed the analogue magnitude system when spontaneously encoding numerosity. The use of the analogue magnitude system may be related to both its low demanding of attentional resources and to the availability of other (non-numerical) quantitative cues which covariate with numerosity.
In Study 1.2, 2 ½ year-old children completed a categorization task in order to investigate their ability in estimating numerical sets. Children’s estimations were independent from the visual characteristics of the stimuli (i.e. perimeter or density) within the OTS capacity. Conversely, the estimation of larger quantities (5-9 dots) was significantly affected by stimuli characteristics: in particular, the increase of perimeter with a constant density appears as the combination of visual characteristics which strongly increases the perceived numerosity.
In Study 2, Preschoolers, Grade 1 and Grade 3 pupils had to map continuous, discrete and symbolic quantities. The results indicated that different mechanisms are involved in the estimation of continuous quantities with respect to numerical (discrete and symbolic) quantities.
In Study 3, we devised a dual-task paradigm to investigate the relation between visual short term memory (VSTM) and subitizing. We found a striking correspondence between the number of elements retained in VSTM and the number of elements that can be subitized.
In Study 4.1, children with developmental dyscalculia (DD) in comorbidity with a profile of Non-Verbal syndrome (NVS) and typically developing (TD) children completed a numerical comparison task. We found a specific deficit in the comparison of numerical quantities in DD-NVS children with respect to TD. In particular, the OTS capacity seems to be reduced in the DD-NVS group as compared to TD.
In Study 4.2, children with developmental dyscalculia (DD) and typically developing (TD) children completed two number-line tasks. Children with DD displayed a less precise estimation of symbolic quantities, thereby suggesting a specific deficit in the number representation with respect to TD children.
In Study 5, individuals with Down Syndrome (DS) and typically developing children matched for both mental (MA) and chronological age (CA) completed two numerical tasks in order to evaluate their ability to compare non-symbolic quantities (i.e. dots) and counting process. Kids with DS showed a specific deficit in comparing small quantities, within OTS capacity, with respect to both MA and CA matched kids. For the comparison of larger quantities, kids with DS displayed a performance similar to MA matched controls but lower as compared to CA matched controls. Finally, the counting ability appears similar between kids with DS and MA matched children
Enumeration skills in Down syndrome
No full textIndividuals with Down syndrome (DS) exhibit various math difficulties which can be ascribed both to global intelligence level and/or to their atypical cognitive profile. In this light, it is crucial to investigate whether DS display deficits in basic numerical skills. In the present study, individuals with DS and two groups of typically developing (TD) children matched for mental and chronological age completed two delayed match-to-sample tasks in order to evaluate the functioning of visual enumeration skills. Children with DS showed a specific deficit in the discrimination of small numerosities (within the subitizing range) with respect to both mental and chronological age matched TD children. In contrast, the discrimination of larger numerosities, though lower than that of chronological age matched controls, was comparable to that of mental age matched controls. Finally, counting was less fluent but the understanding of cardinality seemed to be preserved in DS. These results suggest a deficit of the object tracking system underlying the parallel individuation of small numerosities and a typical - but developmentally delayed - acuity of the approximate number system for discrimination of larger numerosities
Spatial order relates to the exact numerical magnitude of digits in young children
No full textSpatial representation of numbers has been repeatedly associated with the development of numerical and mathematical skills. However, few studies have explored the contribution of spatial mapping to exact number representation in young children. Here we designed a novel task that allows a detailed analysis of direction, ordinality, and accuracy of spatial mapping. Preschool children, who were classified as competent counters (cardinal principle knowers), placed triplets of sequentially presented digits on the visual line. The ability to correctly order triplets tended to decrease with the larger digits. When triplets were correctly ordered, the direction of spatial mapping was predominantly oriented from left to right and the positioning of the target digits was characterized by a pattern of underestimation with no evidence of logarithmic compression. Crucially, only ordinality was associated with performance in a digit comparison task. Our results suggest that the spatial (ordinal) arrangement of digits is a powerful source of information that young children can use to construct the representation of exact numbers. Therefore, digits may acquire numerical meaning based on their spatial order on the number line
The knowledge of the preceding number reveals a mature understanding of the number sequence
Full text link© 2019 There is an ongoing debate concerning how numbers acquire numerical meaning. On the one hand, it has been argued that symbols acquire meaning via a mapping to external numerosities as represented by the approximate number system (ANS). On the other hand, it has been proposed that the initial mapping of small numerosities to the corresponding number words and the knowledge of the properties of counting list, especially the order relation between symbols, lead to the understanding of the exact numerical magnitude associated with numerical symbols. In the present study, we directly compared these two hypotheses in a group of preschool children who could proficiently count (most of the children were cardinal principle knowers). We used a numerosity estimation task to assess whether children have created a mapping between the ANS and the counting list (i.e., ANS-to-word mapping). Children also completed a direction task to assess their knowledge of the directional property of the counting list. That is, adding one item to a set leads to he next number word in the sequence (i.e., successor knowledge) whereas removing one item leads to the preceding number word (i.e., predecessor knowledge). Similarly, we used a visual order task to assess the knowledge that successive and preceding numbers occupy specific spatial positions on the visual number line (i.e., preceding: [?], [13], [14]; successive: [12], [13], [?]). Finally, children's performance in comparing the magnitude of number words and Arabic numbers indexed the knowledge of exact symbolic numerical magnitude. Approximately half of the children in our sample have created a mapping between the ANS and the counting list. Most of the children mastered the successor knowledge whereas few of them could master the predecessor knowledge. Children revealed a strong tendency to respond with the successive number in the counting list even when an item was removed from a set or the name of the preceding number on the number line was asked. Crucially, we found evidence that both the mastering of the predecessor knowledge and the ability to name the preceding number in the number line relate to the performance in number comparison tasks. Conversely, there was moderate/anecdotal evidence for a relation between the ANS-to-word mapping and number comparison skills. Non-rote access to the number sequence relates to knowledge of the exact magnitude associated with numerical symbols, beyond the mastering of the cardinality principle and domain-general factors
Living on the edge: strategic and instructed slowing in the stop signal task
No full textThe stop signal task is widely adopted to assess motor inhibition performance in both clinical and non-clinical populations. Several recent studies explored the influence of strategic approaches to the task. In particular, response slowing seems to be a strategic approach commonly adopted to perform the task. In the present study, we compared a standard version with a strategic version of the task, in which participants were explicitly instructed to slow down responses. Results showed that the instructed slowing did not affect the main inhibition measure, thus confirming the robustness of the stop signal index. On the other hand, it apparently changed the nature of the task, as shown by the lack of correlation between the standard and the strategic versions. In addition, we found a specific influence of individual characteristics on slowing strategies. In the standard version, adherence to task instructions was positively correlated with compliant traits of personality. Despite instructions to maximize response speed, non-compliant participants preferred to adopt a slowing strategy in the standard version of the task, up to a speed level similar to the strategic version, where slowing was required by task instructions. Understanding the role of individual approach to the task seems to be crucial to properly identify how participants cope with task instructions
Spatial and Verbal Routes to Number Comparison in Young Children
Full text linkThe ability to compare the numerical magnitude of symbolic numbers represents a milestone in the development of numerical skills. However, it remains unclear how basic numerical abilities contribute to the understanding of symbolic magnitude and whether the impact of these abilities may vary when symbolic numbers are presented as number words (e.g., “six vs. eight”) vs. Arabic numbers (e.g., 6 vs. 8). In the present study on preschool children, we show that comparison of number words is related to cardinality knowledge whereas the comparison of Arabic digits is related to both cardinality knowledge and the ability to spatially map numbers. We conclude that comparison of symbolic numbers in preschool children relies on multiple numerical skills and representations, which can be differentially weighted depending on the presentation format. In particular, the spatial arrangement of digits on the number line seems to scaffold the development of a “spatial route” to understanding the exact magnitude of numerals
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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