Numerosity capture of attention

Numerosity is informative for living organisms. It can transmit, among many things, amount of food available, heading direction of the troop, which group could win a territorial dispute, the decision of were to build a beehive. Given its ecological importance, we test the hypothesis that numerosity captures visual selection. In five experiments we confirmed that an irrelevant visual stimulus that was numerically large slowed down participants in detecting a task-relevant visual target (Exp. 1 and 2). This capture was not driven by sensory variables that could correlate with numerosity: cumulative area (Exp. 3) and element size (Exp. 4). We also confirmed that the underlying numerosity representations were analogue, not set-based (Exp. 5). In a crowded visual scene numerosity is a relevant cue for visual selection, but represented only in approximate/coarse fashion.