Fig. 3. The persistence of memory is affected by the sequence of continuous and partial reinforcement schedules. (A) Two continuous reinforcement (CR) 45 min training sessions on day 1 followed by two partial reinforcement (PR) training sessions on day 2 produces a long-term memory that persists for at least 3 days. The memory test session was significantly different from session 1 (P<0.01) but not significantly different from the last training session. (B) As in A except that snails first received the PR schedule and then the CR schedule. No memory was formed. The memory test session was not significantly different from session 1 but was significantly different from the last CR session on day 2 (P<0.05). Values are means ± S.E.M. (N=15).