Divided Attention Has Limited Effects on Speech Sensorimotor Control.

Purpose: When vowel formants are externally perturbed, speakers change their production to oppose that perturbation both during the ongoing production (compensation) and in future productions (adaptation). To date, attempts to explain the large variability across individuals in these responses have focused on trait-based characteristics such as auditory acuity, but evidence from other motor domains suggests that attention may modulate the motor response to sensory perturbations. Here, we test the extent to which divided attention impacts sensorimotor control for supralaryngeal articulation.

Method: Neurobiologically healthy speakers were exposed to random (Experiment 1) or consistent (Experiment 2) real-time auditory perturbation of vowel formants to measure online compensation and trial-to-trial adaptation, respectively. In both experiments, participants completed two conditions: one with a simultaneous visual distractor task to divide attention and one without this secondary task.

Results: Divided visual attention slightly reduced online compensation, but only starting > 300 ms after vowel onset, well beyond the typical duration of vowels in speech. Divided attention had no effect on adaptation.

Conclusions: The results from both experiments suggest that the use of sensory feedback in typical speech motor control is a largely automatic process unaffected by divided visual attention, suggesting that the source of cross-speaker variability in response to formant perturbations likely lies within the speech production system rather than in higher-level cognitive processes. Methodologically, these results suggest that compensation for formant perturbations should be measured prior to 300 ms after vowel onset to avoid any potential impact of attention or other higher-order cognitive factors.