Just like newborn animals, young infants, chicks, and guppies have an innate ability to perceive approximate numbers of objects in their visual field. This is often referred to as their ‘number sense.’ However, scientists have questioned whether this number sense is truly innate or if it develops through calibration processes. To investigate this, researchers developed a neural network model based on lateral inhibition, a key mechanism in the nervous system. The model was able to replicate the size and distance effects observed in number-selective neurons without any adjustment in the connection weights. The results confirmed that number sense can indeed emerge through lateral inhibition, independent of learning. This study sheds light on the role of neural mechanisms in our perception of numbers and raises fascinating questions about how our brains process numerical information.

Newborn animals, such as 4-month-old infants, 4-day-old chicks, and 1-day-old guppies, exhibit sensitivity to an approximate number of items in the visual array. These findings are often interpreted as evidence for an innate “number sense.” However, number sense is typically investigated using explicit behavioral tasks, which require a form of calibration (e.g., habituation or reward-based training) in experimental studies. Therefore, the generation of number sense may be the result of calibration. We built a number-sense neural network model on the basis of lateral inhibition to explore whether animals demonstrate an innate “number sense” and determine important factors affecting this competence. The proposed model can reproduce size and distance effects of output responses of number-selective neurons when network connection weights are set randomly without an adjustment. Results showed that number sense can be produced under the influence of lateral inhibition, which is one of the fundamental mechanisms of the nervous system, and independent of learning.

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