991 research outputs found

    Electrophysiological evidence for notation independence in numerical processing

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    BACKGROUND: A dominant view in numerical cognition is that numerical comparisons operate on a notation independent representation (Dehaene, 1992). Although previous human neurophysiological studies using scalp-recorded event-related potentials (ERPs) on the numerical distance effect have been interpreted as supporting this idea, differences in the electrophysiological correlates of the numerical distance effect in symbolic notations (e.g. Arabic numerals) and non-symbolic notations (e.g. a set of visually presented dots of a certain number) are not entirely consistent with this view. METHODS AND RESULTS: Two experiments were conducted to resolve these discrepancies. In Experiment 1, participants performed a symbolic and a non-symbolic numerical comparison task ("smaller or larger than 5?") with numerical values 1–4 and 6–9 while ERPs were recorded. Consistent with a previous report (Temple & Posner, 1998), in the symbolic condition the amplitude of the P2p ERP component (210–250 ms post-stimulus) was larger for values near to the standard than for values far from the standard whereas this pattern was reversed in the non-symbolic condition. However, closer analysis indicated that the reversal in polarity was likely due to the presence of a confounding stimulus effect on the early sensory ERP components for small versus larger numerical values in the non-symbolic condition. In Experiment 2 exclusively large numerosities (8–30) were used, thereby rendering sensory differences negligible, and with this control in place the numerical distance effect in the non-symbolic condition mirrored the symbolic condition of Experiment 1. CONCLUSION: Collectively, the results support the claim of an abstract semantic processing stage for numerical comparisons that is independent of input notation

    Recent developments in particle-based method for simulation of explosive blast

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    To support simulations of blast loading from explosives using the Material Point Method (MPM), preliminary studies of gas expansion in MPM using the recently developed Convected Particle Domain Interpolation (CPDI) integrator, as well as established integrators based on the Generalized Interpolation Material Point (GIMP) method, show that prevailing algorithms for updating the deformation gradient produce results that are often grossly inconsistent with the update of the particle positions. Mapping of velocity to boundary background nodes is analyzed and demonstrated to induce large errors in problems involving large velocities and rapidly changing velocity gradients (common in blast and penetration applications). The error in the velocity cascades to ultimately corrupt other variables, especially the velocity gradient and stress on which it depends. A well-respected code verification process (the method of manufactured solutions) is used to quantify the errors in the update of variables in the MPM using the CPDI interpolator. Different methods based on linear extrapolation were tested for their potential to improve the mapping of the large-deformation velocity fields in blast and penetration, but with only isolated successes in some cases that often worsened results in other cases

    Embodiment and the origin of interval timing: kinematic and electromyographic data

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    Recent evidence suggests that interval timing (the judgment of durations lasting from approximately 500 ms. to a few minutes) is closely coupled to the action control system. We used surface electromyography (EMG) and motion capture technology to explore the emergence of this coupling in 4-, 6-, and 8-month-olds. We engaged infants in an active and socially relevant arm-raising task with 7 cycles and response period. In one condition cycles were slow (every 4 seconds) in another they were fast (every 2 seconds). In the slow condition, we found evidence of time locked sub-threshold EMG activity even in the absence of any observed overt motor responses at all 3 ages. This study shows that EMGs can be a more sensitive measure of interval timing in early development than overt behavior

    A test of the automaticity assumption of compliance tactics: discouraging undergraduate binge drinking by appealing to consistency and reciprocity

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    The mindfulness of compliance with requests making use of the commitment/consistency or the reciprocity principle was investigated. Participants (N = 129) received a foot-in-the-door (FITD) request (commitment/consistency application), a door-in-the-face (DITF) request (reciprocity application), or no request. Next, participants read either a weak or neutral message about the importance of moderate alcohol consumption then reported the likelihood of not drinking excessively for one week (target request). When accompanied by a weak message, the target request elicited less compliance if preceded by the DITF or FITD requests than by no initial request, suggesting compliance tactics sometimes increase thoughtfulness

    Meta-analysis of Clear Cell Renal Cell Carcinoma Gene Expression Defines a Variant Subgroup and Identifies Gender Influences on Tumor Biology

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    Clear cell renal cell carcinoma (ccRCC) displays molecular and histologic heterogeneity. Previously described subsets of this disease, ccA and ccB, were defined based on multigene expression profiles, but it is unclear whether these subgroupings reflect the full spectrum of disease or how these molecular subtypes relate to histologic descriptions or gender

    Processing Ordinality and Quantity: The Case of Developmental Dyscalculia

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    In contrast to quantity processing, up to date, the nature of ordinality has received little attention from researchers despite the fact that both quantity and ordinality are embodied in numerical information. Here we ask if there are two separate core systems that lie at the foundations of numerical cognition: (1) the traditionally and well accepted numerical magnitude system but also (2) core system for representing ordinal information. We report two novel experiments of ordinal processing that explored the relation between ordinal and numerical information processing in typically developing adults and adults with developmental dyscalculia (DD). Participants made “ordered” or “non-ordered” judgments about 3 groups of dots (non-symbolic numerical stimuli; in Experiment 1) and 3 numbers (symbolic task: Experiment 2). In contrast to previous findings and arguments about quantity deficit in DD participants, when quantity and ordinality are dissociated (as in the current tasks), DD participants exhibited a normal ratio effect in the non-symbolic ordinal task. They did not show, however, the ordinality effect. Ordinality effect in DD appeared only when area and density were randomized, but only in the descending direction. In the symbolic task, the ordinality effect was modulated by ratio and direction in both groups. These findings suggest that there might be two separate cognitive representations of ordinal and quantity information and that linguistic knowledge may facilitate estimation of ordinal information
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