The density bias: Capuchin monkeys (Sapajus apella) prefer densely arranged items in a food-choice task

In the current work, we investigated whether capuchin monkeys preferred densely distributed resources to sparsely distributed resources in a 2-choice discrimination task with edible rewards. Capuchin monkeys were biased to select a denser food set over the same number of food items in a sparsely arranged set. Furthermore, increased density of the larger food set facilitated discrimination performance in quantity comparisons with a true difference in set size. These results align with previous studies demonstrating a preference for densely distributed food sets in infants and callitrichid primates, as well as previous evidence of a density bias among several rhesus macaques and capuchin monkeys in a computerized relative quantity discrimination task. Thus, the density bias appears to emerge across multiple domains and presentation formats for some primate species. The role of density in perceived numerosity by capuchin monkeys and other species as it pertains to the foraging domain is discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).