Response-force changes early in extinction with and without a changing force criterion during training

This experiment was designed to examine the question of how different force-exertion requirements in effect prior to extinction affect force exertion during extinction of the previously reinforced response, with an emphasis on such effects early in extinction. Human participants were exposed to one of three conditions in which making a force-exertion response resulted in points displayed on a computer screen. In two conditions, the response-force requirement was fixed during the reinforcement phase at a force exertion of either 50%-65% or 100%-125% of the force criterion exerted in a pretest. During the third condition, the force-exertion criterion was decreased progressively from 100%-125% to 50%-65% of the force criterion during the reinforcement phase. After a short adjustment period, response-force exertions generally conformed to the force requirements for reinforcement. Removing the opportunity for reinforcement reduced the number of responses relative to those occurring in the reinforcement phase, although some responding was still occurring for most participants at the end of the extinction phase. The results are discussed in relation to the variables responsible for the extinction of a force-defined response, emphasizing changes in force early in extinction.