Perception of degraded vocalizations by budgerigars (Melopsittacus undulatus)

Abstract

Three budgerigars were trained with operant techniques to discriminate examples of species-specific contact calls. Once the birds learned the discrimination among a large set of calls, they were tested with the calls altered in various ways. The birds' performance on altered calls was compared with performance on normal calls. Results show that the birds could tolerate large spectral and temporal alterations in the calls with little or no decrement in performance. A comparison of the birds' performance across conditions shows clear evidence of a redundancy in information contained in the calls. The birds were equally adept at discriminating among the calls when given only high-frequency information and when given only low-frequency information. The birds also performed just as well when presented with only the short beginning portions of the calls as they did when presented with somewhat longer portions near the end of the calls. This ability of budgerigars to discriminate among species-specific vocal signals that are highly distorted is reminiscent of the ability of humans to discriminate and recognize highly distorted speech sounds. © 1986 Psychonomic Society, Inc.