The Role of Experience in the Use of Speech Cues by Budgerigars
Flaherty, Mary M.
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The current project investigates how experience with human speech can influence speech perception in budgerigars, vocal mimics whose speech exposure can be tightly controlled in a laboratory setting. The data collected includes behavioral responses from 24 budgerigars, tested using a cue-trading paradigm with synthetic speech. Before testing, the birds were divided into different groups: Passive speech exposure (regular exposure to human speech), No speech exposure (completely isolated), and Speech-trained (using the Model-Rival Method). After the exposure period, all budgerigars were tested for cue trading using operant conditioning procedures. Birds were trained to peck keys in response to different synthetic speech sounds that began with “d” or “t” and that varied in VOT and in the frequency of the first formant at voicing onset. Once training performance criteria were met, budgerigars were presented with the entire series, including ambiguous sounds. The responses on these trials were used to determine which speech cues were used, if cue trading was present, and whether speech exposure had an influence on perception. Cue trading was found in all of the birds. Results indicate that prior speech experience did not influence cue trading. This suggests speech categories are learned auditory categories in budgerigars and may indicate a similar mechanism in humans.