A novel food-delivery device for neurophysiological and neuropsychological studies in monkeys

Neurophysiological and neuropsychological studies in monkeys sometimes require an automated food-pellet dispenser. Commercially available dispensers typically sequester the pellet until delivery and, once delivered, the pellet's availability cannot be controlled. The custom-designed dispenser described here overcomes those two limitations. The device is composed of two separate units: a feeder and an electronic controller. The feeder manipulates food pellets with actuators driven by air pressure and delivers them into a serving bowl. The controller's settings determine whether the monkey can retrieve a pellet from the bowl. If the experiment requires that the pellet be visible and within reach, but unavailable for retrieval, the controller enables a trap-door mechanism at the bottom of the bowl. Any motion near the serving bowl, such as that caused by the approach of a monkey's hand, will then trigger the opening of the trap door, which causes the pellet to fall into an enclosed pellet collector. This rapid pellet-removal mechanism can also be triggered by other computer-controlled contingencies. Two of these dispensers have been in operation in an applied laboratory setting for over 2 years.