Phonological encoding and word stress in stuttering and nonstuttering subjects

One of the main reasons for conducting this priming experiment was to test the hypothesis that stuttering is caused by a phonological encoding deficit. Evidence for this hypothesis was found by Wijnen and Boers (1994) (J Fluency Dis 19, 1-20). Stutterers and nonstutterers were required to utter one response word from a set of five as fast as possible upon visual presentation of a related cue word. In the homogeneous condition, the response words shared the initial consonant or the initial consonant and subsequent vowel. In the heterogeneous condition, response words from different sets were mixed and, as a result, phonemically unrelated. In Wijnen and Boers' study, the difference between these two conditions (the priming effect) was larger in the CV prime condition than in the C prime condition for nonstutterers. For stutterers, priming occurred only when the response words shared both consonant and vowel. These results were taken to indicate that in stutterers the encoding of the stress-bearing part of the syllable is delayed. In the present study, stutterers responded on average slower than nonstutterers, but the crucial effect, i.e., an interaction of prime type (C versus CV) and subject group (stutterers versus nonstutterers) was not reliable. Another purpose of this experiment was to examine the influence of stress upon phonological encoding in nonstutterers and stutterers. The mean reaction time for words stressed on the second syllable was significantly longer than for words stressed on the first syllable, but no significant interaction between subject group and stress position was found. In conclusion, these results do not support the hypothesis that stuttering is specifically related to a difficulty in the phonological encoding of the stress-bearing part of the syllable.