Hesitation phenomena: a dynamical perspective.

The aim of this paper is to test if hesitation phenomena are periodically distributed in spoken language production. Twenty semi-spontaneous descriptions and narratives produced by five healthy male adults were examined in a multiple case study design. Speech was sampled at a 200 ms rate for time series generation. Fourier analysis indicated that all time series were statistically stationary, which means that speech did not become more or less fluent along each sample. Fourier analysis identified periodic cycles of hesitations in all speech samples. Therefore, hesitations were not randomly distributed in speech production; intervals with more occurrences of hesitations regularly alternated with intervals with fewer occurrences. Thus, hesitations behaved as stable phenomena that could be anticipated. The median and the mean lengths of hesitation cycles were about 9 and 13 s, respectively. It is suggested that macroplanning activities (selecting and ordering information) are language processes compatible with this time scale. Three hesitation cycles were usually identified in each sample, suggesting that spoken language processing occurs in parallel within working memory, with the resources being shared by different processes.