Frequency scaling of unimanual 90° rhythmic coordination: Data and model

Two rhythmic coordinations, 0° and 180° relative phase, can be performed stably at preferred frequency (~1 Hz) without training. Evidence indicates that these behavioral modes entail detection of the relative direction of movement that is used as perceptual information to control and coordinate performance. At higher frequencies, this yields instability of 180° and spontaneous transition to 0°. The ability to perform a 90° coordination can be acquired by learning to detect and use relative position as information. Herth, Zhu and Bingham (2021) found that skilled performance of 90° bimanual coordination exhibits mode switching to 0° or 180° with frequency scaling. Unlike the switching from 180° to 0°, transition from a learned coordination to 0° or 180° entails a change in information. They found that neither this switching nor performance of corrections to resist switching entailed intentional decisions during performance. Relatedly, they found that correction is not intrinsic to skilled performance of 90°. They successfully simulated results of frequency scaling of 90° using an extended Bingham model in which switching and correction were initiated as the information for 90° fell below threshold. We now attempt to replicate these findings testing unimanual 90° coordination with noninterference and correcting instructions. With correcting in the previous study, bimanual 90° coordination remained stable at all frequencies while noninterference instructions yielded mode switching at higher frequencies. Snapp-Childs, Wilson and Bingham (2011) showed that unimanual coordination switches at much lower frequencies than bimanual coordination. It is significantly less stable due to coupling that is unidirectional. The current finding was that unimanual performance of 90° fails to remain stable even with correcting at higher frequencies. Results were simulated using a unimanual version of the extended Bingham model.