How visual is the “groupitizing”? The impact of visual deprivation over its emergence

Previous research showed that people enumerate objects faster and more accurately when they form clusters, a phenomenon called "groupitizing". While mainly studied visually, its dependence on vision is unclear. Congenitally blind (CB) individuals provide a critical test: if vision is essential, CB people should lack groupitizing; if not, they may apply it across modalities, potentially outperforming sighted participants. We compared CB and sighted adults on an auditory groupitizing task, based on the estimation of 5-12 pure tones presented either randomly or grouped by temporal proximity. Both groups showed lower errors and higher precision for grouped sequences, confirming that groupitizing can emerge without visual experience. Importantly, for larger numerosities, sighted individuals' grouping benefit decreased, whereas CB participants maintained robust advantages across all set sizes. These findings suggest that groupitizing relies on amodal perceptual mechanisms and that congenital blindness may enhance auditory enumeration strategies.