Diadochokinesis Performance and Its Link to Cognitive Control: Alternating Versus Non-Alternating Diadochokinesis.

Purpose: In a previous publication, we observed that maximum speech performance in a nonclinical sample of young adult speakers producing alternating diadochokinesis (DDK) sequences (e.g., rapidly repeating "pataka") was associated with cognitive control: Those with better cognitive switching abilities (i.e., switching flexibly between tasks or mental sets) showed higher DDK accuracy. To follow up on these results, we investigated whether this previously observed association is specific to the rapid production of alternating sequences or also holds for non-alternating sequences (e.g., "tatata").

Method: For the same sample of 78 young adults as in our previous study, we additionally analyzed their accuracy and rate performance on non-alternating sequences to investigate whether executive control abilities (i.e., indices of speakers' updating, inhibition, and switching abilities) were more strongly associated with production of alternating, as compared with non-alternating, sequences.

Results: Of the three executive control abilities, only switching predicted both DDK accuracy and rate. The association between cognitive switching (and updating ability) and DDK accuracy was only observed for alternating sequences. The DDK rate model included a simple effect of cognitive switching, such that those with better switching ability showed slower diadochokinetic rates across the board. Thus, those with better cognitive ability showed more accurate (alternating) diadochokinetic production and slower maximum rates for both alternating and non-alternating sequences.

Conclusion: These combined results suggest that those with better executive control have better control over their maximum speech performance and show that the link between cognitive control and maximum speech performance also holds for non-alternating sequences.