TRAVEL, SENSITIVITY TO REINFORCEMENT, AND MULTIPLE ALTERNATIVES

Abstract

When rats search for food in eight alternatives concurrently available and climb barriers to travel from one site to another, the distributions of times and responses often lag behind those of the reinforcers. This result may reflect the way in which the barriers are introduced into the situation. The present experiment explored this possibility with rats. Concurrent schedules of reinforcement with random interval components of different values provided food in eight levers mounted in four chambers connected to a central platform. First, the rats were allowed to enter the chambers and switch from one lever to another without restrictions. Then access to the chambers was obstructed and the levers separated from one another by 300-mm-high barriers. Finally, the height of the barriers was increased from 300 to 700 mm. The shortest visit times, giving-up times, and giving-up responses were produced when rats visited the levers without restrictions. With the barriers in place these measures increased, reaching higher values when barrier height was increased. For responses, sensitivity to reinforcement, as estimated by the parameter s of the generalized matching law, increased with increasing travel requirement, indicating a tendencytoward overmatching. However, for time allocation only one rat showed the same tendency.Key words: Choice, multiple alternatives, travel, sensitivity, rats