De novo learning versus adaptation of continuous control in a manual tracking task

Learning to perform feedback control is critical for learning many real-world tasks that involve continuous control such as juggling or bike riding. However, most motor learning studies to date have investigated how humans learn feedforward but not feedback control, making it unclear whether people can learn new continuous feedback control policies. Using a manual tracking task, we explicitly examined whether people could learn to counter either a 90˚ visuomotor rotation or mirror-reversal using feedback control. We analyzed participants9 performance using a frequency domain system identification approach which revealed two distinct components of learning: 1) adaptation of baseline control, which was present only under the rotation, and 2) de novo learning of a continuous feedback control policy, which was present under both rotation and mirror reversal. Our results demonstrate for the first time that people are capable of acquiring a new, continuous feedback controller via de novo learning.