Complex dynamic processes in sign tracking with an omission contingency (negative automaintenance).

Hungry pigeons received food periodically, signaled by the onset of a keylight. Key pecks aborted the feeding. Subjects responded for thousands of trials, despite the contingent nonreinforcement, with varying probability as the intertrial interval was varied. Hazard functions showed the dominant tendency to be perseveration in responding and not responding. Once perseveration was accounted for, a linear operator model of associative conditioning further improved predictions. Response rates during trials were correlated with the prior probabilities of a response. Rescaled range analyses showed that the behavioral trajectories were a kind of fractional Brownian motion.