Studies on instrumental learning have rarely been conducted with tailed amphibians. This may be due primarily to difficulties in training newts with food rewards. Most previous studies on instrumental learning by newts have employed runways without a distinct discriminative stimulus associated with food. In this study, we trained newts (Cynops pyrrhogaster) with black rings as the discriminative stimuli at close distance (5 cm ahead). Two newts were trained to pass through one ring with a diameter of 8 cm. One newt failed to show evidence of learning (i.e., decreased response time) with 14 sessions of massed trials (4 trials/session). The second newt, however, learned to pass through rings with diameters of 8, 6, 5, and 4 cm. A 20-trial follow-up probe test was conducted with the second newt, in which the 4-cm black ring and a novel red square were presented side by side. The newt did not choose the black ring over the red square in any of the trials, suggesting that neither the black color nor the circle shape drove the newt’s behavior. In a retention test conducted 185 days later, the newt did not pass through the ring of 4 cm at all, suggesting that this behavior was learned but not retained after 6 months. Presentations of distinctive stimuli in close proximity might enhance appetitive instrumental learning by newts, which is otherwise difficult to accomplish using runway apparatuses with no distinctive cues to elicit instrumental behaviors.
The basis of affectively motivated helping of another in distress has long been debated by scholars in diverse disciplines. Work in rodents that took place more than 50 years ago suggested that rodents participate in affective communication. Now the author's laboratory has established an ethical and feasible test for rodent helping behavior that involves one rat freeing another from a plastic tube. The helping exhibited is consistent, reinforced, socially selective, and independent of immediate social contact. A recent modified version of the helping behavior test confirms that rats help a conspecific in need. In sum, the complex social behavior, expressed by rodents and primates including humans, validates the notion that mammals share a phylogenetic inheritance that promotes other-oriented affective behavior.