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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).

We assessed metacognitive monitoring in 3- to 5-year-old preschool children using a non-verbal behavioral paradigm of confidence. Children responded to a variety of computerized tasks, during which rewards could be collected after each trial at a location spatially distant from the computer. Critically, auditory cues indicating performance were delayed by five seconds after each trial. A metacognitive response indicating confidence in their performance would lead children to move towards the reward location before receiving trial feedback. Results indicated that early movements reflected confidence and non-movements reflected uncertainty. Movements differed as a function of task performance (correct vs. incorrect responding) and objective trial difficulty (easier vs. harder trials) across most cognitive tasks. For some tasks, performance and metacognitive movements also varied as a function of age. These data, from a non-verbal measure of confidence, match other reports of emerging metacognition in children in this age range.