“…Intertrial reinforcement: Large number of trials. Berg, Connelly, and Duerfeldt (1969), Black and Spencc (1965), and Spence, Platt, and Matsumoto (1965) found a partial reinforcement effect when a large number of acquisition trials were used even with intertrial reinforcement. This could indicate that a few of the Ni, N 2 , Ns, • • •, are not removed entirely by the intertrial reinforcement, and after a sufficiently large number of trials, enough of them have become conditioned to running to increase the resistance to extinction.…”