Task complexity and manual reaction times in people who stutter

The study was designed to test the hypothesis that manual reaction time differences between people who stutter and those who do not reflect the information processing complexity of the task. The study focused on decision complexity in a reaction time paradigm. One manipulation involved increasing the number of response alternatives. The second involved the spatial contiguity of signal and response locus. Twenty-four adult stutterers and 24 nonstutterers were compared with respect to response initiation and completion times on the various task conditions. Contrary to the hypothesis, there was no significant Group x Complexity interaction in the analysis of either response measure for either complexity manipulation. Stutterers were slower than nonstutterers overall, but with increasing decision complexity, the group response times paralleled one another. It is concluded that whatever response planning and organization deficit there may be in people who stutter, it is independent of decision complexity but may be evident in manipulations of response complexity defined in terms of spatial and temporal coordination.