Hesitation in speech can... um... help a listener understand.

This paper investigates the effect of disfluencies on listeners' on-line processing of speech. More specifically, it tests the hypothesis that filled pauses like um, which tend to occur before words that are low in accessibility, act as a signal to the listener that a relatively inaccessible word is about to be produced.

Two experiments are reported, in which participants followed recorded instructions to press buttons corresponding to images on a computer screen. In 50% of trials, the spoken name of the image was preceded by um. In experiment 1, the intrinsic accessibility of the target items was manipulated (by means of lexical frequency); in experiment 2, the extrinsic (visual) accessibility varied. Both experiments demonstrated that participants were quicker to respond when a target was preceded by um, regardless of whether the item referred to was difficult to access or not. In addition, in experiment 2 there was a weak interaction between accessibility and presence or absence of an um. We present the data here as early evidence that listeners can benefit from disfluencies in others' speech, and outline some methodological and theoretical considerations and further experiments.