Fig. 5. Yoked controls do not show augmentation of long-term memory (LTM) retention. (A) A cohort of 15 naïve snails received three yoked control intermediate-term memory (ITM) training sessions. Three hours later, they received the LTM training procedure. Learning was evident (ANOVA, F_14,2=15.2849 P<0.0001; session 6 was significantly different from session 4, P<0.01), but memory was not present when tested 72 h after the last LTM training session: there was a significant difference between session 6 and the memory test (MT) (P<0.01) but no significant difference between MT and session 4 (NSD, P>0.05). (B) Another naïve cohort of snails (N=15) received three yoked control ITM training sessions. Eight hours later, they received the LTM training procedure. Learning was evident (ANOVA, F_14,2=11.7037 P<0.0002; session 6 was significantly different from session 4, P<0.01) but memory was not present when tested 72 h after the last LTM training session: there was a significant difference between session 6 and MT (P<0.01) but no significant difference between MT and session 4 (NSD, P>0.05).