Adaptive forgetting in Iberian green frog tadpoles (Pelophylax perezi): learned irrelevance and latent inhibition may avoid predator misidentification.

Predator recognition often requires learning by prey individuals. Iberian green frog tadpoles (Pelophylax perezi) have the ability to learn to recognize new potential predators when their chemical cues are found paired with conspecific alarm cues. However, a random pairing of alarm cues and chemical stimuli of a nonpredator might later induce costly antipredator responses to nondangerous species. Here, we studied the potential existence in this frog species of two phenomena (learned irrelevance and latent inhibition) that could help tadpoles to avoid these nonadaptive responses to chemical cues of nonpredator species. Our results showed that, when tadpoles experienced a random pattern of presence of alarm cues alone or predator cues alone over the 4 days before or after the simultaneous detection of these two cues paired, no learned association was formed. These results showed the existence of an effect of learned irrelevance on learning in Iberian green frog tadpoles. Also, tadpoles clearly inhibited the formation of a learning association between predator and alarm cues after a 4-day period during which they had been exposed to the predator cues alone. This result showed the existence of an effect of latent inhibition on learning about cues related to increased predation risk. Thus, both learned irrelevance and latent inhibition, rather than being considered to be failed predator recognition, can rather be seen as adaptive ways for dealing with conflicting information and as strategies to avoid learning irrelevant information and costly antipredatory responses to nonpredatory stimuli.