Incongruence in number–luminance congruency effects

Congruency tasks have provided support for an amodal magnitude system for magnitudes that have a “spatial” character, but conflicting results have been obtained for magnitudes that do not (e.g., luminance). In this study, we extricated the factors that underlie these number–luminance congruency effects and tested alternative explanations: (unsigned) luminance contrast and saliency. When luminance had to be compared under specific task conditions, we revealed, for the first time, a true influence of number on luminance judgments: Darker stimuli were consistently associated with numerically larger stimuli. However, when number had to be compared, luminance contrast, not luminance, influenced number judgments. Apparently, associations exist between number and luminance, as well as luminance contrast, of which the latter is probably stronger. Therefore, similar tasks, comprising exactly the same stimuli, can lead to distinct interference effects

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

Double Dissociation of Format-Dependent and Number-Specific Neurons in Human Parietal Cortex

Based on neuroimaging methods, it is a commonly held view that numerical representation in the human parietal lobes is format independent. We used a transcranial magnetic stimulation adaptation paradigm to examine the existence of functionally segregated overlapping populations of neurons for different numerical formats and to reveal how numerical information is encoded and represented. Based on 2 experiments, we found that right parietal lobe stimulation showed a dissociation between digits and verbal numbers, whereas the left parietal lobe showed a double dissociation between the different numerical formats. Further analysis and modeling also excluded pre- or postrepresentational components as the source of the current effects. These results demonstrate that both parietal lobes are equipped with format-dependent neurons that encode quantity

Making sense of number words and Arabic digits: Does order count more?

The ability to choose the larger between two numbers reflects a mature understanding of the magnitude associated with numerical symbols. The present study explores how the knowledge of the number sequence and memory capacity (verbal and visuospatial) relate to number comparison skills while controlling for cardinal knowledge. Preschool children’s (N = 140, Mage‐in‐months = 58.9, range = 41–75) knowledge of the directional property of the counting list as well as the spatial mapping of digits on the visual line were assessed. The ability to order digits on the visual line mediated the relation between memory capacity and number comparison skills while controlling for cardinal knowledge. Beyond cardinality, the knowledge of the (spatial) order of numbers marks the understanding of the magnitude associated with numbers

Who gains more: experts or novices? The benefits of interaction under numerical uncertainty

Interacting to reach a shared decision is an omnipresent component of human collaboration. We explored the interaction between dyads of individuals with different levels of expertise. The members of the dyads completed a number line task privately, jointly and privately again. In the joint condition, dyad members shared their private estimates and then negotiated a joint estimate. Both dyad members averaged their private individual estimates to determine joint estimates, thereby showing a strong equality bias. Their performance in the joint condition exceeded the performance of the dyad’s best estimator, demonstrating interaction benefit, only when the dyad members had similar levels of expertise and when the averaged dyad performance was sufficiently accurate. At the end of the task, participants rated their and their partner’s level of competence. Participants were accurate in classifying themselves as the expert or the novice within the dyad. Nevertheless, novices tended to overestimate their ability as they admitted to being less competent but only slightly worse than their expert partner. Experts, instead, believed themselves to be more competent but were humble and considered their performance only marginally better than their partner. Overall, these results have important implications for settings in which people with different levels of expertise interact

Better Together? The Cognitive Advantages of Synaesthesia for Time, Numbers and Space

Synaesthesia for time, numbers and space (TNS synaesthesia) is thought to have costs and benefits for recalling and manipulating time and number. There are two competing theories about how TNS synaesthesia affects cognition. The ‘magnitude’ account predicts TNS synaesthesia may affect cardinal magnitude judgements, whereas the ‘sequence’ account suggests it may affect ordinal sequence judgements and could rely on visuospatial working memory. We aimed to comprehensively assess the cognitive consequences of TNS synaesthesia and distinguish between these two accounts. TNS synaesthetes, grapheme-colour synaesthetes and non-synaesthetes completed a behavioural task battery. Three tasks involved cardinal and ordinal comparisons of temporal, numerical and spatial stimuli; we also examined visuospatial working memory. TNS synaesthetes were significantly more accurate than non-synaesthetes in making ordinal judgements about space. This difference was explained by significantly higher visuospatial working memory accuracy. Our findings demonstrate an advantage of TNS synaesthesia which is more in line with the sequence account

GABA Predicts Time Perception

Our perception of time constrains our experience of the world and exerts a pivotal influence over a myriad array of cognitive and motor functions. There is emerging evidence that the perceived duration of subsecond intervals is driven by sensory-specific neural activity in human and nonhuman animals, but the mechanisms underlying individual differences in time perception remain elusive. We tested the hypothesis that elevated visual cortex GABA impairs the coding of particular visual stimuli, resulting in a dampening of visual processing and concomitant positive time-order error (relative underestimation) in the perceived duration of subsecond visual intervals. Participants completed psychophysical tasks measuring visual interval discrimination and temporal reproduction and we measured in vivo resting state GABA in visual cortex using magnetic resonance spectroscopy. Time-order error selectively correlated with GABA concentrations in visual cortex, with elevated GABA associated with a rightward horizontal shift in psychometric functions, reflecting a positive time-order error (relative underestimation). These results demonstrate anatomical, neurochemical, and task specificity and suggest that visual cortex GABA contributes to individual differences in time perception

Perceived state of self during motion can differentially modulate numerical magnitude allocation.

Although a direct relationship between numerical-allocation and spatial-attention has been proposed, recent research suggests these processes are not directly coupled. In keeping with this, spatial attention shifts induced either via visual or vestibular motion can modulate numerical allocation in some circumstances but not in others. In addition to shifting spatial attention, visual or vestibular motion-paradigms also (i) elicit compensatory eye-movements which themselves can influence numerical-processing and (ii) alter the perceptual-state of-"self", inducing changes in bodily self-consciousness impacting upon cognitive mechanisms. Thus, the precise mechanism by which motion modulates numerical-allocation remains unknown. We sought to investigate the influence that different perceptual experiences of motion have upon numerical magnitude allocation whilst controlling for both eye-movements and task-related effects. We first used optokinetic visual-motion stimulation (OKS) to elicit the perceptual experience of either "visual world" or "self"-motion during which eye movements were identical. In a second experiment we used a vestibular protocol examining the effects of perceived and subliminal angular rotations in darkness, which also provoked identical eye movements. We observed that during the perceptual experience of "visual-world" motion, rightward OKS biased judgments towards smaller numbers, whereas leftward OKS biased judgments towards larger numbers. During the perceptual experience of "self-motion", judgments were biased towards larger numbers irrespective of the OKS direction. Contrastingly, vestibular motion perception was found not to modulate numerical magnitude allocation, nor was there any differential modulation when comparing "perceived" versus "subliminal" rotations. We provide a novel demonstration that magnitude-allocation can be differentially modulated by the perceptual state of-self during visual-motion. This article is protected by copyright. All rights reserved

Psychobiotic interventions for anxiety in young people: a systematic review and meta-analysis, with youth consultation

The human gut microbiome influence on brain function and mental health is an emerging area of intensive research. Animal and human research indicates adolescence as a sensitive period when the gut-brain axis is fine-tuned, where dietary interventions to change the microbiome may have long-lasting consequences for mental health. This study reports a systematic review and meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, with discussion of a consultation on the acceptability of psychobiotic interventions for mental health management amongst youth with lived experience. Six databases were searched for controlled trials in human samples (age range: 10–24 years) seeking to reduce anxiety. Post intervention outcomes were extracted as standard mean differences (SMDs) and pooled based on a random-effects model. 5416 studies were identified: 14 eligible for systematic review and 10 eligible for meta-analysis (total of 324 experimental and 293 control subjects). The meta-analysis found heterogeneity I2 was 12% and the pooled SMD was −0.03 (95% CI: −0.21, 0.14), indicating an absence of effect. One study presented with low bias risk, 5 with high, and 4 with uncertain risk. Accounting for risk, sensitivities analysis revealed a SMD of −0.16 (95% CI: −0.38, 0.07), indicative of minimal efficacy of psychobiotics for anxiety treatment in humans. There is currently limited evidence for use of psychobiotics to treat anxiety in youth. However, future progress will require a multidisciplinary research approach, which gives priority to specifying mechanisms in the human models, providing causal understanding, and addressing the wider context, and would be welcomed by anxious youths

Implicit response-irrelevant number information triggers the SNARC effect : Evidence using a neural overlap paradigm

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