Perceptual Constraints on Frequency Ratio Performance in Motor-Respiratory Coordination

Abstract

In motor-respiratory coordination, people typically maintain frequency ratios that are from lower levels of a mathematical structure known as the Farey tree. A hypothesized mechanism for motor-respiratory coordination is the visceral piston (Bramble & Carrier, 1983)—mechanical loading of the lungs due to footfalls, for example, imposes a rhythm on breathing. The occurrence of motor-respiratory coordination in exercises in which there is no visceral piston (e.g., bicycling and wheelchair propulsion) implies that there are other mechanisms. We examined whether there is a perceptual basis for motor-respiratory coordination. In Experiment 1, participants viewed simulated ratios side by side and, in a forced-choice paradigm, judged whether they were the same or different. In Experiment 2, participants performed ratios using feedback displays in which different ratios looked either the same or different. Lower level ratios were less likely than higher level ratios to be confused with other ratios. Ratios that could be distinguished perceptually were performed more accurately and less variably than ratios that appeared the same.

Notes

¹In this article, we adhere to the conventional format in the motor-respiratory coordination literature (as opposed to the modeling literature) of identifying movement-to-breathing ratios (usually p ≥ q). In the Farey tree and other depictions of the sine circle map (e.g., the Arnold tongues), 1:0 and 1:1 represent the numerical boundaries of Ω. That is, all ratios in the Farey tree are on the interval from 0 to 1 so that, for example, 2:1 = 1:2 = 0.5. Ratios produced at higher levels of the Farey tree fill in the spaces between existing ratios. For example, 3:1 = 1:3 = 0.333 is between 1:0 and 2:1.

*p < .05.

**p < .01.

***p < .001. df = (1, 24) for all comparisons.