Is the Force of Response Shaped by Reinforcement?

Abstract

This article reviews whether reinforcement can shape the force of a response. In rats, when only forceful responses are reinforced, the force of response increases. At first glance, this increase in force suggests that force can be shaped like any other aspect of the response. However, the increase in force occurs immediately and appears to be a result of the frustration effect as described by Amsel. On subsequent trials, there is little increase in force of response or in the proportion of reinforced trials, suggesting that reinforcing only forceful responses does not shape the appropriate force of response. Consistent with this hypothesis, studies of humans concerning the control of movement suggest that the force of a movement may be neither remembered nor under direct volitional control. If the force of response is not influenced by reinforcers, the process of producing a response can be divided into two stages, one that is influenced by reinforcers and one that is not.