Fig. 2: Operant conditioning of syllable repetition.

a The repetition of the target syllables in songs was analyzed online by SAIBS. If the repetition number of the target syllable “c” exceeds the predetermined threshold “x”, the reward movie was presented from a monitor. b Example of song spectrograms before and after the conditioning (Top). The daily shift of max repetition counts in nine birds (Below). Mean ± s.e.m. c–e Change of syllable repetition with conditioning (c) and without conditioning (d), and with conditioning with non-social feedback movie (e). The box plot shows median and first and third quantiles with mean shown as circles; P values, two-sided paired t-test, t(8) = −10.5, n = 9 (c), t(4) = −0.384, n = 5 (d), and t(4) = −1.15, n = 5 (e). f Shift of song rate of songs of each repetition before and after conditioning. Pink shadings, the rewarded range. Mean ± s.e.m.; P values, two-sided paired t-test (left, middle), t(5) = 3.41, n = 6. The summary (left, middle) and results from each bird (right) are shown. The reward range is highlighted in pink. The heatmap shows the song rate change (%) for each bird.