Uh and um revisited: are they interjections for signaling delay?

Clark and Fox Tree (2002) have presented empirical evidence, based primarily on the London-Lund corpus (LL; Svartvik & Quirk, 1980), that the fillers uh and um are conventional English words that signal a speaker's intention to initiate a minor and a major delay, respectively. We present here empirical analyses of uh and um and of silent pauses (delays) immediately following them in six media interviews of Hillary Clinton. Our evidence indicates that uh and um cannot serve as signals of upcoming delay, let alone signal it differentially: In most cases, both uh and um were not followed by a silent pause, that is, there was no delay at all; the silent pauses that did occur after um were too short to be counted as major delays; finally, the distributions of durations of silent pauses after uh and um were almost entirely overlapping and could therefore not have served as reliable predictors for a listener. The discrepancies between Clark and Fox Tree's findings and ours are largely a consequence of the fact that their LL analyses reflect the perceptions of professional coders, whereas our data were analyzed by means of acoustic measurements with the PRAAT software (www.praat.org). A comparison of our findings with those of O'Connell, Kowal, and Ageneau (2005) did not corroborate the hypothesis of Clark and Fox Tree that uh and um are interjections: Fillers occurred typically in initial, interjections in medial positions; fillers did not constitute an integral turn by themselves, whereas interjections did; fillers never initiated cited speech, whereas interjections did; and fillers did not signal emotion, whereas interjections did. Clark and Fox Tree's analyses were embedded within a theory of ideal delivery that we find inappropriate for the explication of these phenomena.