Surely a monkey can discriminate two bananas from three bananas in order to choose the bunch with the greater amount of food. But when they make their choice, do they rely on number or some other stimulus attribute such as amount of yellow? If a monkey were able to make pure numerical discriminations, what would this say about her conceptual understanding of number? Do monkeys manipulate their representations of quantity using mathematical operations such as ordering, addition, and subtraction?

The Brannon lab uses psychophysical tools to investigate these questions and to probe the mechanisms by which monkeys represent number without language. Monkeys are trained in touch screen tasks to respond to pictures for juice reward.