Persistent pigeons (Columba livia) learn how to produce a list.

In the Featured Article for this issue of the Journal of Comparative Psychology, Scarf, Johnston, and Colombo (2018) showed that pigeons learned to reproduce (by pecking icons presented on a screen) a four-item serially ordered list without specific training on that list, as macaques did (Figure 1). In Scarf et al.'s (2018) study, all five birds given structured training subsequently mastered multiple sets of two-item, then three-item, and finally four-item lists, with a diminishing training regime for the later four-item lists. Scarf et al.'s (2018) findings have at least two important implications for our science: First, members of evolutionarily distant taxa, pigeons and monkeys, can both produce a serially ordered set of four actions. Second, we are reminded that learning sets can be acquired for diverse tasks-the principles of learning set formation are very general. (PsycINFO Database Record