The Role of Speech Experience on Cue Trading in Parakeets
Speech perception is a crucial element in the process of human vocal communication, but there are many unanswered questions about the role speech experience plays in this process. This research investigates if experience with human speech sounds will influence speech perception in budgerigars. Budgerigars are vocal mimics and their experience with human speech sounds can be easily controlled in a laboratory setting. The data were collected from 30 budgerigars that were divided into four different exposure groups: passive group with regular exposure to human speech, no speech exposure group - isolated from all human speech sounds, and two speech trained groups, one group trained to produce words beginning with the target sounds that they are tested on – “d” and “t” and the other group trained to produce non-target sounds. Speech training was done using the Model-Rival method popularized by Irene Pepperberg. After approximately 6 months of exposure, the budgerigars were trained using an operant conditioning method to peck keys in response to synthetic speech sounds. The sounds varied in two important acoustic cues that have been found to influence speech perception in humans. After the initial training phase, they were moved to the testing phase where they were tested on a cue trading procedure involving ambiguous sounds that varied between “da” and “ta”. This was to see if there is a difference in the use of speech cues between the different exposure groups. Preliminary results show a difference in perception as a function of exposure group. The largest cue trading effects were found in the speech-isolated group, indicating that prior speech experience is not necessary for this phenomenon. These findings could have very important implications for understanding human speech perception.