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AbstractBehavioral research suggests that two cognitive systems are at the foundations of numerical thinking: one for representing 1–3 objects in parallel and one for representing and comparing large, approximate numerical magnitudes. We tested for dissociable neural signatures of these systems in preverbal infants by recording event‐related potentials (ERPs) as 6–7.5‐month‐old infants (n = 32) viewed dot arrays containing either small (1–3) or large (8–32) sets of objects in a number alternation paradigm. If small and large numbers are represented by the same neural system, then the brain response to the arrays should scale with ratio for both number ranges, a behavioral and brain signature of the approximate numerical magnitude system obtained in animals and in human adults. Contrary to this prediction, a mid‐latency positivity (P500) over parietal scalp sites was modulated by the ratio between successive large, but not small, numbers. Conversely, an earlier peaking positivity (P400) over occipital‐temporal sites was modulated by the absolute cardinal value of small, but not large, numbers. These results provide evidence for two early developing systems of non‐verbal numerical cognition: one that responds to small quantities as individual objects and a second that responds to large quantities as approximate numerical values. These brain signatures are functionally similar to those observed in previous studies of non‐symbolic number with adults, suggesting that this dissociation may persist over vast differences in experience and formal training in mathematics.

AbstractTwo non‐verbal cognitive systems, an approximate number system (ANS) for extracting the numerosity of a set and a parallel individuation (PI) system for distinguishing between individual items, are hypothesized to be foundational to symbolic number and mathematics abilities. However, the exact role of each remains unclear and highly debated. Here we used an individual differences approach to test for a relationship between the spontaneously evoked brain signatures (using event‐related potentials) of PI and the ANS and initial development of symbolic number concepts in preschool children as displayed by counting. We observed that individual differences in the neural signatures of the PI system, but not the ANS, explained a unique portion of variance in counting proficiency after extensively controlling for general cognitive factors. These results suggest that differences in early attentional processing of objects between children are related to higher‐level symbolic number concept development.

AbstractHumans are born with the ability to mentally represent the approximate numerosity of a set of objects, but little is known about the brain systems that sub‐serve this ability early in life and their relation to the brain systems underlying symbolic number and mathematics later in development. Here we investigate processing of numerical magnitudes before the acquisition of a symbolic numerical system or even spoken language, by measuring the brain response to numerosity changes in pre‐verbal infants using functional near‐infrared spectroscopy (fNIRS). To do this, we presented infants with two types of numerical stimulus blocks: number change blocks that presented dot arrays alternating in numerosity and no change blocks that presented dot arrays all with the same number. Images were carefully constructed to rule out the possibility that responses to number changes could be due to non‐numerical stimulus properties that tend to co‐vary with number. Interleaved with the two types of numerical blocks were audio‐visual animations designed to increase attention. We observed that number change blocks evoked an increase in oxygenated hemoglobin over a focal right parietal region that was greater than that observed during no change blocks and during audio‐visual attention blocks. The location of this effect was consistent with intra‐parietal activity seen in older children and adults for both symbolic and non‐symbolic numerical tasks. A distinct set of bilateral occipital and middle parietal channels responded more to the attention‐grabbing animations than to either of the types of numerical stimuli, further dissociating the specific right parietal response to number from a more general bilateral visual or attentional response. These results provide the strongest evidence to date that the right parietal cortex is specialized for numerical processing in infancy, as the response to number is dissociated from visual change processing and general attentional processing.

AbstractThe ability to decode and accurately identify information from facial emotions may advantage young children socially. This capacity to decode emotional information may likewise be influenced by individual differences in children's temperament. This study investigated whether sensory reactivity and perceptual awareness, two dimensions of temperament, as well as children's ability to accurately label emotions relates to the neural processing of emotional content in faces. Event related potentials (ERPs) of 4 to 6 year‐old children (N = 119) were elicited from static displays of anger, happy, fearful, sad, and neutral emotion faces. Children, as a group, exhibited differential early (N290) and mid‐latency (P400) event‐related potentials (ERPs) in response to facial expressions of emotion. Individual differences in children's sensory reactivity were associated with enhanced P400 amplitudes to neutral, sad, and fearful faces. In a separate task, children were asked to provide an emotional label for the same images. Interestingly, children less accurately labeled the same neutral, sad, and fearful faces, suggesting that, contrary to previous work showing enhanced attentional processing to threatening cues (i.e., fear), children higher in sensory reactivity may deploy more attentional resources when decoding ambiguous emotional cues.