Reaction-time signatures reveal divergent cognitive strategies underlying numerical decisions in monkeys and crows

Non-symbolic numerical competence, supported by the approximate number system (ANS), is widespread across animals, yet it remains unclear whether similar numerical performance reflects shared cognitive mechanisms. We compared two rhesus monkeys and two carrion crows on an extended delayed match-to-numerosity task. Animals viewed a sample numerosity (one to four), maintained it across a delay, and searched sequentially through up to three test displays for a match. Behavioral accuracy was compara