A reliable method for continuously monitoring motor activity in unrestrained squirrel monkeys

A simple, reliable, and inexpensive method for measuring spontaneous motor activity in unrestrained squirrel monkeys is described. In this method, the home cage is suspended within a wooden enclosure in a way that allows the cage to swing in any lateral direction. This movement is recorded by two brass cylinders connected to the home cage and to the fixed wooden enclosure, respectively. The brass cylinders act as electrical contacts that serve to trigger an electronic recording device. The method is extremely sensitive.