Do as I do imitation in a steller sea lion Eumetopias jubatus.

The present study explored whether a well-socialized Steller sea lion named Hama could reproduce similar actions with human demonstrations using the "Do as I do" (DAID) paradigm. Hama had learned 50 types of behaviors, but her social learning ability was unknown. In Study 1, we trained Hama to produce simultaneous DAID responses. After introducing the DAID training, we conducted four tests to confirm Hama's acquisition of demonstrator-matching behavior. We found that Hama successfully acquired the action-matching ability for human actions, not only with three trained actions but also with six out of seven untrained actions (see Test 1 and Test 2). Moreover, Hama's DAID performance was stable regardless of the familiarity of human demonstrators (see Test 1 and Test 2). Hama successfully performed two completely novel body actions that were not included in her prior learning repertoire, but failed to replicate actions involving object manipulation (see Test 3). She showed no response in control trials without demonstrations, providing partial evidence for negative control (see Test 4). In Study 2, we introduced Hama to performing non-simultaneous DAID responses, which involved suppressing immediate simultaneous actions following the demonstrator and then reproducing the actions upon the verbal cue "Go." She accurately performed the DAID response even when she delayed her response until the demonstrator's demonstration was completed (Test 5). Importantly, she reproduced the action accurately when visual contact between the demonstrator and herself was blocked after the demonstration, eliminating the Clever Hans effect as a potential influence on her simultaneous DAID response (Test 6). However, she could not reproduce small or untrained actions (Test 7). These results suggest that Hama may be able to accurately map human action sequences in body-oriented actions to some extent. This study provides the first evidence of motor imitation ability in captive pinnipeds.