Fig. 3. Controls for the KCl bath experiments. Top, snails (N=19) that were placed in pond water (PW) rather than the KCl bath before 30 min of training did not have memory at 24 h. Bottom, snails (N=12) that were exposed to KCl and then yoke (i.e. non-contingently) trained showed no significant difference in the number of attempted pneumostome openings from naive levels, demonstrating that LTM was not formed. Reprinted from Neurobiology of Learning and Memory 87, 391–403 (2007) with permission from Elsevier (Martens et al., 2007a).