What effect can rhythmic finger tapping have on the phonological similarity effect?

The effects of rhythmic finger tapping on the phonological similarity effect were investigated in two experiments. In both, subjects were tested for serial recall of visually presented letter sequences that were either phonologically similar or dissimilar. The letter sequences had to be remembered under three tapping conditions: right-hand tapping, left-hand tapping, and a no-tapping control. Experiment 1 showed clear phonological similarity effect in both the control and the left-hand tapping conditions, but not in the right-hand tapping condition, when recall responses were written with the right hand. When the number of tapping practice trials was fixed at two and recall was vocal in Experiment 2, the phonological similarity effect was eliminated in both the right-hand and the left-hand tapping conditions. These results suggest that some form of speech motor programs played an important role in serial recall.