Nesting material as a reinforcer for female mice

Seven virgin female mice of strain RAP (albino) were trained to key-press, using paper as a reinforcer. Their behaviour was recorded when paper was delivered non-contingently, and when it was contingent upon key-pressing on CRF and FR schedules. When the contingency was introduced, the number of pieces of paper taken decreased. As fixed ratio size was increased, the overall response rate remained constant, and the reinforcement rate declined. The sequence of nest-building activities which accompanied delivery of paper was also observed to change as a function of schedule.