A computer analysis of serial interactions in spaced responding.

Serial dependencies in interresponse times were studied by means of a digital computer. In monkeys exposed to a DRL 20-sec schedule of reinforcement, serial interactions appeared at all stages of training. Early in training the serial effects consisted of trains of relatively long interresponse times interspersed among trains of relatively short ones. Later on, the serial effects appeared to be characterized by a tendency to drift up and down in long wavelength periods around the minimum interval required for reinforcement. After training to a point at which most interresponse times produced reinforcement, serial effects of a still more subtle nature appeared. These effects were made apparent by autocorrelation and power spectrum methods and consisted of both long-term and extremely short-term fluctuations in interresponse times.