Variability control in speech production tasks performed by adults and children.

Eighteen adults and 12 children, ranging from 7 to 11 years of age, participated in a study that investigated their abilities to control the temporal variability of their speech. For both the adults and the children, few substantive differences in performance were observed when considering control data versus findings from an experimental task in which they were specifically instructed to be as consistent as possible in producing various stimuli. Although some subjects did show reduced variability in the experimental condition, there was little evidence that such decreases typically represented more than random effects. In general, the results suggest that when producing multiple repetitions of words and short phrases, adults and 7-11-year-old children are essentially as consistent as they can be, whether specifically attempting to minimize variability or not. The basis for this could be that even in control conditions, subjects may perform at or near optimal levels of consistency across productions.