Francesco Sella

High Impact = High Statistical Standards? Not Necessarily So

What are the statistical practices of articles published in journals with a high impact factor? Are there differences compared with articles published in journals with a somewhat lower impact factor that have adopted editorial policies to reduce the impact of limitations of Null Hypothesis Significance Testing? To investigate these questions, the current study analyzed all articles related to psychological, neuropsychological and medical issues, published in 2011 in four journals with high impact factors: Science, Nature, The New England Journal of Medicine and The Lancet, and three journals with relatively lower impact factors: Neuropsychology, Journal of Experimental Psychology-Applied and the American Journal of Public Health. Results show that Null Hypothesis Significance Testing without any use of confidence intervals, effect size, prospective power and model estimation, is the prevalent statistical practice used in articles published in Nature, 89%, followed by articles published in Science, 42%. By contrast, in all other journals, both with high and lower impact factors, most articles report confidence intervals and/or effect size measures. We interpreted these differences as consequences of the editorial policies adopted by the journal editors, which are probably the most effective means to improve the statistical practices in journals with high or low impact factors.

Enumeration skills in Down syndrome

Individuals 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.

Basic and advanced numerical performances relate to mathematical expertise but are fully mediated by visuospatial skills.

Recent studies have highlighted the potential role of basic numerical processing in the acquisition of numerical and mathematical competences. However, it is debated whether high-level numerical skills and mathematics depends specifically on basic numerical representations. In this study mathematicians and nonmathematicians performed a basic number line task, which required mapping positive and negative numbers on a physical horizontal line, and has been shown to correlate with more advanced numerical abilities and mathematical achievement. We found that mathematicians were more accurate compared with nonmathematicians when mapping positive, but not negative numbers, which are considered numerical primitives and cultural artifacts, respectively. Moreover, performance on positive number mapping could predict whether one is a mathematician or not, and was mediated by more advanced mathematical skills. This finding might suggest a link between basic and advanced mathematical skills. However, when we included visuospatial skills, as measured by block design subtest, the mediation analysis revealed that the relation between the performance in the number line task and the group membership was explained by non-numerical visuospatial skills. These results demonstrate that relation between basic, even specific, numerical skills and advanced mathematical achievement can be artifactual and explained by visuospatial processing.

Training numerical skills with the adaptive videogame “The Number Race”: A randomized controlled trial on preschoolers

Adaptive computer games offer an attractive method for numeracy training in young children. However, the evidence for transfer of learning to standard measures of numerical and arithmetic skills is scarce. We carried out a randomized controlled trial on a sample of preschool children of middle socio-economic status to evaluate the effectiveness of the freeware videogame “The Number Race” (Wilson et al., 2006). Children were randomly assigned to the training group or to the control group performing an alternative computer-based activity matched for duration and setting. The groups were matched for age, gender, and IQ. Training yielded large improvements in mental calculation and spatial mapping of numbers, as well as smaller improvements in the semantic representation of numbers. Our findings complement previous studies that showed beneficial effects for disadvantaged children, thereby suggesting that “The Number Race” is a valuable tool for fostering mathematical learning in the general population of young children.

Neuropsychology is nothing without control: a potential fallacy hidden in clinical studies.

The need of appropriate methodological approaches in cognitive neuropsychology has been repeatedly addressed for over 30 years. Most of the debate has focused on whether single-case or group studies are more appropriate for drawing inferences with respect to an unimpaired cognitive architecture (e.g., Caramazza and McCloskey, 1988; Grodinsky et al., 1999). This controversy has not been resolved in either direction and, currently, both single-cases and group studies are commonly adopted in neuropsychological research. We will focus our attention upon the latter approach and will maintain that the presence of a control group does not per se guarantee an appropriate interpretation of results. According to the group study approach, an experimental groupof braindamagedpatients is typically selectedaccording to specific diagnostic tests or criteria; then an age-matched non-pathological control group is also selected on the same tests/criteria. These two groups are usually required to perform a task, which is the focus of the study. Then, in discussing the results, the immediate (and rather naı̈ve) conclusion is to ascribe the differences between the two groups to the presence/absence of the specific pathology. Here is where the fallacy can be incurred: the control group often differs from the experimental group, not only because of the absence of the pathology, but also because it lacks other characteristics, associated with the pathology itself. If we select a group of patients on the basis of their performance in a test for a specific neuropsychological deficit (e.g., anosognosia, apraxia, etc.) we are in fact selecting patients with that deficit and with a high probability of associated (often cognitive) impairments against patients (or healthy participants)

Using Functional Neuroimaging to Test Theories of Cognition: A Selective Survey of Studies from 2007 to 2011 as a Contribution to the Decade of the Mind Initiative

The aim of the present literature survey is to estimate how many of the studies recently made available in journals devoted to cognitive neuroscience have actually pursued Goal 2, in terms of evaluating theories of cognition. Expressed in another way, the aim of the present paper is to estimate how many recent neuroimaging studies actually comprise relevant ways of exploring the human mind, thus giving rise to new disciplines as a critical contribution to the Decade of the Mind Initiative (Albus et al., 2007).

Varieties of quantity estimation in children.

In the number-to-position task, with increasing age and numerical expertise, childrens pattern of estimates shifts from a biased (nonlinear) to a formal (linear) mapping. This widely replicated finding concerns symbolic numbers, whereas less is known about other types of quantity estimation. In Experiment 1, Preschool, Grade 1, and Grade 3 children were asked to map continuous quantities, discrete nonsymbolic quantities (numerosities), and symbolic (Arabic) numbers onto a visual line. Numerical quantity was matched for the symbolic and discrete nonsymbolic conditions, whereas cumulative surface area was matched for the continuous and discrete quantity conditions. Crucially, in the discrete condition childrens estimation could rely either on the cumulative area or numerosity. All children showed a linear mapping for continuous quantities, whereas a developmental shift from a logarithmic to a linear mapping was observed for both nonsymbolic and symbolic numerical quantities. Analyses on individual estimates suggested the presence of two distinct strategies in estimating discrete nonsymbolic quantities: one based on numerosity and the other based on spatial extent. In Experiment 2, a non-spatial continuous quantity (shades of gray) and new discrete nonsymbolic conditions were added to the set used in Experiment 1. Results confirmed the linear patterns for the continuous tasks, as well as the presence of a subset of children relying on numerosity for the discrete nonsymbolic numerosity conditions despite the availability of continuous visual cues. Overall, our findings demonstrate that estimation of numerical and non-numerical quantities is based on different processing strategies and follow different developmental trajectories.

Strategy Selection in ADHD Characteristics Children: A Study in Arithmetic

Objective: It has been argued that ADHD characteristics children have difficulties in selecting the best strategy when they accomplish cognitive tasks. The detrimental influence of these poor strategy skills may be crucial for several aspects of academic achievement such as mathematical learning. Method: Fourth- and fifth-grade children with ADHD symptoms and matched controls were asked to select the better of two rounding strategies in a computational estimation task (i.e., finding the best estimate of two-digit addition problems). Results: (a) Both control and ADHD children correctly executed a selected strategy, (b) ADHD children selected the best strategy less often than controls, (c) ADHD took more time to estimate sums of two-digit addition problems and provided poorer estimates, and (d) different factors predicted best strategy selections in each group. Conclusion: These findings have important implications for further understanding the sources of differences in cognitive performance between ADHD and control children.(J. of Att. Dis. 2019; 23(1) 87-98)

Preschool children use space, rather than counting, to infer the numerical magnitude of digits: Evidence for a spatial mapping principle

A milestone in numerical development is the acquisition of counting principles which allow children to exactly determine the numerosity of a given set. Moreover, a canonical left-to-right spatial layout for representing numbers also emerges during preschool. These foundational aspects of numerical competence have been extensively studied, but there is sparse knowledge about the interplay between the acquisition of the cardinality principle and spatial mapping of numbers in early numerical development. The present study investigated how these skills concurrently develop before formal schooling. Preschool children were classified according to their performance in Give-a-Number and Number-to-position tasks. Experiment 1 revealed three qualitatively different groups: (i) children who did not master the cardinality principle and lacked any consistent spatial mapping for digits, (ii) children who mastered the cardinality principle and yet failed in spatial mapping, and (iii) children who mastered the cardinality principle and displayed consistent spatial mapping. This suggests that mastery of the cardinality principle does not entail the emergence of spatial mapping. Experiment 2 confirmed the presence of these three developmental stages and investigated their relation with a digit comparison task. Crucially, only children who displayed a consistent spatial mapping of numbers showed the ability to compare digits by numerical magnitude. A congruent (i.e., numerically ordered) positioning of numbers onto a visual line as well as the concept that moving rightwards (in Western cultures) conveys an increase in numerical magnitude mark the mastery of a spatial mapping principle. Children seem to rely on this spatial organization to achieve a full understanding of the magnitude relations between digits.

Living on the edge: strategic and instructed slowing in the stop signal task

The 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.