内外部分组线索对数量感知分组化策略的影响——来自fMRI证据

Numerosity perception refers to the cognitive ability of humans to extract numerical information from various stimuli. It serves as a fundamental basis for understanding the world and processing information, thereby guiding and influencing human behavior and decision-making. Grouping strategies, also known as "groupitizing," involve organizing objects into sets or categories during numerosity perception processes. This facilitates rapid and effective numerosity estimation, particularly in situations with short presentation times and numerous quantities. Groupitizing combines the advantages of subitizing and counting, thereby influencing individual arithmetic abilities. Previous research has predominantly focused on investigating the groupitizing of numerosity perception based on intrinsic grouping cues. However, it has overlooked the influence of both intrinsic and extrinsic cues of perceptual grouping on numerosity perception during groupitizing. Previous studies, spanning the visual and numerosity perception domains, consistently indicate that extrinsic grouping cues exhibit stronger grouping advantages than intrinsic grouping cues. Therefore, this study employs a numerosity estimation task to separately examine the effects of intrinsic grouping cues (such as color similarity and proximity) and extrinsic grouping cues (including common region and connectedness) on numerosity perception during groupitizing. The aim is to uncover the neural mechanisms underlying groupitizing. This study recruited 21 university students as participants. A block design was employed for the functional Magnetic Resonance Imaging (fMRI) task. Stimulus presentation and generation utilized MATLABs PsychToolbox (version R2016b). The stimuli comprised four factors: grouping condition (grouping, no-grouping), grouping cues (extrinsic grouping cues, intrinsic grouping cues), and numerosity (6, 9, 12, 16). MRI scans for the numerosity estimation task were conducted using Siemens 3.0 T technology, synchronously collecting brain functional data. Participants were instructed to press the corresponding number of points they estimated based on the stimuli presented on the screen. We compared the functional activation between the grouping and no-grouping conditions, as well as between extrinsic and intrinsic grouping cues. Additionally, to assess the relationship between these variables, we employed the Pearson product-moment correlation method. The results firstly unveil the critical role of the bilateral intraparietal sulcus (IPS) in numerosity perception, particularly showing significant activation during the quantity processing stage. Specifically, activation was observed in the IPS during numerosity perception tasks, indicating its involvement in processing numerical information. Secondly, it was found that both grouped and ungrouped conditions activate cortical regions associated with quantity estimation, such as the precentral gyrus and inferior temporal gyrus. Under the grouped condition, additional activation was observed in brain regions related to computation, including the superior frontal gyrus, intraparietal sulcus, and angular gyrus, exhibiting a left hemisphere lateralization advantage. This indicates that participants tend to utilize computational and retrieval strategies under the grouped condition compared to the ungrouped condition, which suggests a more efficient processing mechanism. Lastly, the results also reveal that extrinsic grouping cues, relative to intrinsic grouping cues, activate additional brain regions associated with topological properties such as the middle frontal gyrus and inferior temporal gyrus. This uncovers the topological invariance characteristic of extrinsic grouping cues in the intrinsic mechanism of numerosity perception grouping strategies, highlighting the influence of extrinsic cues on neural processing mechanisms. The findings of this study suggest that participants tend to rely more on mental arithmetic and factual retrieval when employing grouping strategies, aiming to enhance the efficiency of numerosity perception. This sheds further light on why grouping strategies are comparatively more efficient than other approaches. Moreover, the mechanism of extrinsic grouping cues in numerosity perception strategies demonstrates topological invariance, presenting a unique advantage in perceptual processing. This discovery provides direct neural evidence for the significance of topological properties in numerosity perception, thereby deepening our understanding of numerosity perception and its neural underpinnings.