Figure 5.

Contingent-dependent increase in rate of radula biting. A, Sample recordings of successive onsets of bite cycles (vertical bars) during a test period at 1 h after training (according to protocols in Fig. 4) in a control (1), a contingently rewarded (2), and a noncontingently rewarded (3) animal. B, Group comparison. The rate of biting was higher after contingent-reward stimulation than in control or noncontingent animals [control vs contingent, q₃ = 4.750; contingent vs noncontingent, q₂ = 6.463; control vs noncontingent, q₂ = 0.626, not significant (n.s.)].