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In the field of numerical cognition, researchers conventionally assess nonsymbolic numerical abilities with the help of number comparison tasks, in which participants need to compare two arrays. Many studies emphasized that visual (non-numerical) dimensions can serve as strategic cues and influence the decision on numerosity in these tasks. In this study, we suggest the use of a novel paradigm based on the change detection paradigm. Here, participants had to simultaneously pay attention to numerical changes and visual changes on a target non-numerical dimension (individual area, total area, field area, or density). Participants had to detect changes relative to the two dimensions and press response keys indicating either number change or visual change or press both keys. In such a double change detection paradigm, and unlike number comparison tasks, target and covarying dimensions cannot serve as cues to influence the numerical decision. We found that numerical change detection was excellent and stable across the conditions. Further, participants were more likely to falsely consider visual changes as numerical changes than the other way around. Lastly, when both dimensions varied, participants more frequently missed visual changes than numerical changes. Overall, our findings show that numerosity was the most salient visual dimension. From a methodological perspective, such a double change detection paradigm could be of critical interest to assess numerical abilities for future studies. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Humans possess a numerical intuition that allows them to manipulate large non-symbolic quantities. This ability has been broadly assessed with the help of number comparison tasks involving simultaneously displayed arrays. Many authors pointed out that the manipulation (or the lack thereof) of non-numerical features deeply impacts performance in these tasks, but the specific nature of this influence is not clear. The current study investigates the interaction between numerical and non-numerical quantity judgment tasks. Adult participants performed five distinct comparison tasks, each based on a target dimension: numerosity, total area, dot size, convex hull, and mean occupancy. We manipulated the relation between the target and the other dimensions to measure their respective influence on task performance. Results showed that total area and convex hull substantially affected numerosity comparisons. The number of dots conversely acted as an informative dimension when participants had to make a decision based on the total area or the convex hull. Our results illustrate that adults flexibly use non-target dimensions as visual cues to perform comparison judgments. Overall, this suggests that the influence found in numerical comparison tasks is explicit and deliberate rather than due to implicit visual integration processes., info:eu-repo/semantics/published

Humans and other animal species are endowed with the ability to sense, represent, and mentally manipulate the number of items in a set without needing to count them. One central hypothesis is that this ability relies on an automated functional system dedicated to numerosity, the perception of the discrete numerical magnitude of a set of items. This system has classically been associated with intraparietal regions, however accumulating evidence in favor of an early visual number sense calls into question the functional role of parietal regions in numerosity processing. Targeting specifically numerosity among other visual features in the earliest stages of processing requires high temporal and spatial resolution. We used frequency-tagged magnetoencephalography to investigate the early automatic processing of numerical magnitudes and measured the steady-state brain responses specifically evoked by numerical and other visual changes in the visual scene. The neuromagnetic responses showed implicit discrimination of numerosity, total occupied area, and convex hull. The source reconstruction corresponding to the implicit discrimination responses showed common and separate sources along the ventral and dorsal visual pathways. Occipital sources attested the perceptual salience of numerosity similarly to both other implicitly discriminable visual features. Crucially, we found parietal responses uniquely associated with numerosity discrimination, showing automatic processing of numerosity in the parietal cortex, even when not relevant to the task. Taken together, these results provide further insights into the functional roles of parietal and occipital regions in numerosity encoding along the visual hierarchy., info:eu-repo/semantics/published