The Influence of Movement Preparation Time on the Expression of Visuomotor Learning and Savings

Abstract

Following a change in the environment or motor apparatus, human subjects are able to rapidly compensate their movements to recover accurate performance. This ability to adapt is thought to be achieved through multiple, qualitatively distinct learning processes acting in parallel. It is unclear, however, what the relative contributions of these multiple processes are during learning. In particular, long-term memories in such paradigms have been extensively studied through the phenomenon of savings-faster adaptation to a given perturbation the second time it is experienced-but it is unclear which components of learning contribute to this effect. Here we show that distinct components of learning in an adaptation task can be dissociated based on the amount of preparation time they require. During adaptation, we occasionally forced subjects to generate movements at very low preparation times. Early in learning, subjects expressed only a limited amount of their prior learning in these trials, though performance improved gradually with further practice. Following washout, subjects exhibited a strong and persistent aftereffect in trials in which preparation time was limited. When subjects were exposed to the same perturbation twice in successive days, they adapted faster the second time. This savings effect was, however, not seen in movements generated at low preparation times. These results demonstrate that preparation time plays a critical role in the expression of some components of learning but not others. Savings is restricted to those components that require prolonged preparation to be expressed and might therefore reflect a declarative rather than procedural form of memory.

Time-dependent competition between habitual and goal-directed response preparation

“…In order to unmask potential habitual selection of the original response, we forced participants to act at different response times, ranging from 0-1200 ms, using a forced-response paradigm 17,23,24 ( Figure 3a). Four tones were played, each separated by 400ms, and participants were instructed that they must make a response synchronously with the final tone.…”

“…This implies that both mappings were represented during each trial, demonstrating the existence of multiple components of learning. The relative expression of different components of learning has previously been shown to be influenced by limiting cognitive resources 26,27 , including available preparation time 17,20,22,28,29 . However, previous research has manipulated preparation time in a relatively simple 'high-or-low' manner 17,20 , or based on spontaneous variations in 'voluntarily' selected reaction times 29 .…”

“…Despite these parallels, selection skill could also improve through alternative means; for instance, by learning to execute necessary computations more efficiently 16,17 , or through more P a g e 4 o f 3 5…”

“…A habitually selected response might be only transiently prepared, and later replaced by a more deliberately determined response. Indeed, limiting preparation time has proven to be an effective means of prohibiting deliberate, goal-directed processes from influencing behavior 17,[20][21][22] . We therefore predicted that imposing limited preparation time would unmask such latent habitually selected responses.…”

Savings upon Re-Aiming in Visuomotor Adaptation

“…In contrast, recent work has shown that the pattern of behavior observed in visuomotor savings experiments is often inconsistent with an error-based process, and may be better explained as reflecting changes in action selection that facilitate performance (Huang et al, 2011;Haith et al, 2015;Huberdeau et al, 2015;McDougle et al, 2015;Orban de Xivry and Lefévre, 2015).…”