Physical causal understanding in rodents: tool-use behavior in rats

Abstract

Many studies have reported that wild and captive nonhuman primates have an advanced ability to understand causal relationships and use tools. However, the only studies investigating physical causal understanding in rodents under controlled experimental settings has been conducted in degus. The present studies conducted tool-use tasks in rats in an experimental setting, similar to tasks conducted in nonhuman primates and birds, and we used newly developed tasks to investigate their ability for physical causal understanding. In these tasks, rats were required to use tools to obtain food beyond their reach. Research 1 showed that rats chose appropriate tools to obtain food even when two novel tools were presented. In addition, Research 2 showed that rats were able to manipulate a tool according to the position of food. Our studies first suggest that rats have a primitive ability to understand physical causal relationships between pulling tools and approaching food. We propose the rat as an animal model to shed light on the evolution of physical causal understanding from rodents to humans.