Figure 1.

Diagram of the experimental plan for one subject. Horizontal lines depict stimuli presented during tests 1 and 2 and during tutoring. N, nuttalli dialect; O, oriantha dialect; H, heterospecific song; G, generalization song, in this case two novel nuttalli dialects. A few days after fledging, the bird heard playback of five stimuli in recognition (R) trials and two pairs of habituation/dishabituation stimuli in discrimination (D) trials (for examples of stimuli and text for description of protocol, see Fig. 2). This bird was then tutored for 10 days with the two nuttalli stimuli, and then the recognition and discrimination trials were repeated in test 2. No heterospecific song was presented in test 2; instead, two generalization stimuli were presented. After test 2, all birds were tutored with the same eight novel dialects for 40 days. The time axis is not to scale; for a given bird tests 1 and 2 took place on a single day.