Michael L. Dent
Elizabeth F. Powell
Alisa Pierce
Robert J. Dooling
Dept. of Psychol., Univ. of Maryland, College Park, MD 20742
The perception of speech sounds by animals provides important comparative data for understanding the perception of speech by humans. Using operant conditioning procedures, three budgerigars (Melopsittacus undulatus) were trained and then tested on their ability to discriminate among tokens of synthetic /ba-wa/ speech continua. A ``short'' (120 ms) and a ``long'' (320 ms) continuum were constructed, each consisting of 10 stimuli. For both the long and the short /ba-wa/ stimuli, budgerigars showed a marked improvement in discrimination near the human phonetic boundary. Similar to humans, budgerigars were significantly less sensitive to transition changes in the long syllables compared with the short syllables, suggesting that they may be susceptible to backward masking by the syllable of longer length. Two of the three budgerigars also showed a shift in their phonetic boundaries with changes in syllable length. These data extend the evidence of similarities between birds and mammals in the perception of speech sound contrasts. [Work supported by NIH Grants DC00198 and MH00982 to RJD.]