Differences between stutterers' and nonstutterers' short-term recall and recognition performance.

Longer rehearsal times presumably reduce the efficiency of rehearsal and, hence, of short-term recall. The present experiment examined the question as to whether the slower subvocalization rate of people who stutter is correlated with inferior short-term serial recall and recognition performance. Rate of overt articulation was taken as a measure of rehearsal time. Lists of four nonlexical CVC syllables were presented for short-term serial recall and for short-term recognition. Nineteen adults who stutter and 30 nonstutterers participated in the experiment. In the serial reproduction task the subjects who stuttered reproduced significantly fewer items correctly than did nonstutterers. Recognition performance was measured by nonparametric measures of sensitivity and bias as defined in signal detection theory. The stuttering subjects had a significantly lower sensitivity resulting primarily from a higher false alarm rate. Rate of overt articulation was significantly related to one measure of short-term recall but not to the sensitivity of recognition. These results were interpreted as suggesting that people who stutter have slower phonological encoding and rehearsal times, that they make less use of nonphonological forms of coding than do nonstutterers, and that within their phonological system, activation more easily spills over to similar items.