| Mathematics is a science that studies quantitative relationships and spatial forms.Numeracy,as one of the abilities of numbers,plays an important role in compulsory education.In non-symbolic numerical processing,non-symbolic stimuli are generally represented by a group of dot arrays,and the quantity relationship is inferred by visual features.Attention load primarily investigates the allocation,selection,and response control of attentional resources under the constraint of limited capacity.Attention load considered that the processing of target stimuli depends on the extent to which distracting stimuli are processed because of the limited availability of attention resources.There has been ongoing debate about how numerical values and non-symbolic features are processed in non-symbolic numerical processing.This study attempts to find explanations from the perspective of attention resource’s selection and cognitive control.Therefore,potential mechanisms are divided based on the numerical values range according to the three regimes for numerosity perception at first step,and forming two research perspectives: numerosity mechanism and texture-density mechanism.In this context,perceptual load primarily manipulates changes in spatial orientation and color.Spatial orientations and colors need to be remembered in high perceptual load,while low perceptual load conditions,only color features need to be remembered.Cognitive load requires participants to memorize a series of numbers,with sequential or reverse order sequences representing low cognitive load,and scrambled sequences representing high cognitive load.By varying the load levels,the aim is to investigate the changes in attentional resources during non-symbolic numerical processing.Further,based on the theory of response-selection bottleneck and the sensitivity,we add time intervals and presentation time factors for firmed how stable of the results.Finally,cognitive load conditions adopted event-related potential technology for considering the control of attention resources.All experiments are conducted on college students as the subjects.In the end,five studies consisting of 10 experiments are conducted,which including 8behavioral experiments and 2 event-related potential experiments.Study 1 is aimed at investigating whether the level of perceptual load affects non-symbolic numerical processing by behavioral dual-task paradigm.Results show lower accuracy and longer reaction time in the high load perceptual condition in experiment 1.This suggests that the numerosity mechanism incurs greater attentional resource consumption and time cost more under high perceptual load,while the perception threshold and sensitivity are not affected by perceptual load.Experiment 2results show lower accuracy and longer reaction time in the high load condition,with a significant difference in variability coefficient between high and low load conditions in the density range of the texture-density mechanism.It indicates that the texture-density mechanism of non-symbolic numerical processing also incurs greater attentional resource consumption and time cost more under high perceptual load,while changes in attention resources affect the sensitivity of the texture-density mechanism.Study 2 employed the dual-task paradigm with overlapping tasks to re-examine the influence of perceptual load levels on non-symbolic numerical processing.The results only revealed a significant difference in the coefficient of variation in the numerosity mechanism(Experiment 3).This indicates that changes to the paradigm affect the time cost and sensitivity of the numerosity mechanism.Texture-density mechanism only results show differences in accuracy between high and low perceptual load conditions(Experiment 4).This suggests that the texture-density mechanism does not have an advantage under the overlapping dual-task paradigm.Study 3 investigated the influence of limited attentional resources on non-symbolic numerical processing by manipulating the time interval using the dual-task paradigm.The results revealed that participants had higher accuracy and shorter response times under low perceptual load conditions compared to high perceptual load conditions(Experiment 5).It indicates that the limited attentional resources affect numerosity mechanism.It shows that higher accuracy and shorter average reaction time under low perceptual load(Experiment 6).Comparing the results of Experiments 2 and 4,the time intervals affects the attention time cost of the texture-density mechanism,and it has better performance without spending more attentional time cost for the texture-density mechanism under low perceptual load.These differences indicate that the texture-density mechanism flexibly adjusts its processing mode according to changes in attentional resources.Study 4’ s goal is to investigate the effect of presentation time on non-symbolic numerical processing by dual-task paradigm with overlapping tasks.Results show significant differences in accuracy and reaction time between high and low perceptual load levels,and presentation time has a significant main effect on reaction time.Presentation time and load have a significant interaction effect on the subjective equivalence point.This indicates that presentation time affects the numerosity mechanism under low perceptual load(Experiment 7).Compared with Experiment 3,it suggests that presentation time adjusts the perception threshold of numerosity mechanism under low perceptual load,but has no effect on sensitivity.Experiment 8results also show significant differences in accuracy and reaction time between high and low perceptual load levels,presentation time has a significant main effect on reaction time.It shows that the variance of presentation time results is also significant and the highest score obtained at 500 ms under conditions of high perceptual load.The main effect of presentation time on coefficient of variation is significant under conditions of low perceptual load and the highest score obtained at 500 ms.These findings indicate that presentation time affects the perceptual threshold and sensitivity of the texture-density mechanism.Study 5 employs event-related potentials(ERPs)to investigate the neural mechanisms of non-symbolic numerical processing under different cognitive load levels.The results reveal that the numerosity mechanism showing higher brain activation in the parietal P3 component under low cognitive load compared to high cognitive load conditions(Experiment 9).The texture-density mechanism exhibites C1,N1,and P3 components in both the parietal and occipital lobes,with the occipital N1 showing higher brain activation under low cognitive load,and the parietal P3 being more active under low cognitive load(Experiment 10).These findings indicate differential control of attentional resources by the texture-density mechanism,with early occipital N1 and late parietal P3,which demonstrate that the brain activity of the numerosity mechanism and the texture-density mechanism are different.To summarize,the two dual-task paradigms have different effects on the numerosity mechanism and the texture-density mechanism.The numerosity mechanism has an advantage in serial processing(overlapping dual-task paradigm),while the texture-density mechanism could adjust its processing strategy along with the changes of attention resources.Time intervals in overlapping dual-tasks affects the texture-density mechanism,which indicating it prefers parallel processing in the early stages of attention resources.Numerosity mechanism and the texture-density mechanism have different better sensitivity on different presentation time,the texture-density mechanism has the best sensitivity when the presentation time is500 ms.Furthermore,the presentation time is also influenced by changes in attentional resources,and its impact on sensitivity differs between high and low perceptual load levels.Finally,when combining the three regimes for numerosity perception with the theory of sensory integration,we revealing different utilization of attentional resources about the numerosity mechanism and the texture-density mechanism.the results indicate that the numerosity mechanism may form two integrators in serial processing to interpret and evaluate the respective properties of stimuli before outputting response selection.The texture-density mechanism weights visual feature information when attention resources are not tense,and obtaining a comprehensive sensory output.When attention resources are tense,it compares the information in an integrator and finally outputs response selection. |
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