Figure 2.

(A) Sonograms of natural contact calls recorded from two different birds and their synthetic analogs. The full test set consisted of 5 natural calls and 5 synthetic analogs presented in random order. (B) The hit rate or percent correct (mean +/− SD) for each of 3 budgerigars discriminating among the five natural contact calls and their synthetic analogs before treatment with kanamycin and at various times during recovery. The false alarm rate remained well below 10% for all three birds and showed no significant change across test sessions. The discrimination performance of two birds eventually returned to preinjection levels or better while one bird was still significantly impaired even after 23 weeks of recovery.