This paper studies the frequency and distribution of filled pauses (FPs) in ecologically valid data where unaware and authentic customers called in to report problems with their telephony and/or Internet services and were met by a novel Wizard-of-Oz paradigm using real call center agents as wizards. The data analyzed were caller utterances following a directed or an open disambiguation prompt. While no significant differences in FP production were observed as a function of prompt type, FP frequency was found to be considerably higher than what is usually reported in the literature. Moreover, a higher proportion of utterance-initial FPs than normally reported was also observed. The results are compared to previously reported FP frequencies. Potential implications for data collection methodology are discussed.

Index Terms. filled pauses, Wizard-of-Oz, WOZ, speech planning, speech production, many-options, data collection, open prompts, directed prompts, call center, dialog systems.