Explicit and Implicit Processes Constitute the Fast and Slow Processes of Sensorimotor Learning

Abstract

A popular model of human sensorimotor learning suggests that a fast process and a slow process work in parallel to produce the canonical learning curve (Smith et al., 2006). Recent evidence supports the subdivision of sensorimotor learning into explicit and implicit processes that simultaneously subserve task performance (Taylor et al., 2014). We set out to test whether these two accounts of learning processes are homologous. Using a recently developed method to assay explicit and implicit learning directly in a sensorimotor task, along with a computational modeling analysis, we show that the fast process closely resembles explicit learning and the slow process approximates implicit learning. In addition, we provide evidence for a subdivision of the slow/implicit process into distinct manifestations of motor memory. We conclude that the two-state model of motor learning is a close approximation of sensorimotor learning, but it is unable to describe adequately the various implicit learning operations that forge the learning curve. Our results suggest that a wider net be cast in the search for the putative psychological mechanisms and neural substrates underlying the multiplicity of processes involved in motor learning.

Savings upon Re-Aiming in Visuomotor Adaptation

“…Additionally, the results indicate that the larger performance changes observed with large perturbations is primarily due to changes in the explicit aiming process. Indeed, the magnitude of implicit adaptation appears to be relatively constant for the small and large perturbations (Bond and Taylor, 2015).…”

“…However, these models cannot account for a well-described phenomenon in learning, savings (Krakauer et al, 2005;Zarahn et al, 2008). Savings is defined as faster learning when information is presented a second time after being forgotten, compared with the rate of initial learning (Ebbinghaus, 1913;).…”

Delayed feedback during sensorimotor learning selectively disrupts adaptation but not strategy use

“…We designed experiment 3 to examine one such process, an explicit aiming strategy. To this end, we employed an aiming report task that allows for the continuous assessment of how participants modify their aim when faced with a visuomotor perturbation and, by inference, allows a continuous estimate of implicit adaptation McDougle et al 2015;Taylor et al 2014). Since the timing of outcome-based feedback did not produce marked effects on the various measures of learning in experiments 1 and 2, we only tested participants in the No-Delay and Delay conditions.…”

“…To assess the use of aiming strategies, we employed an aiming report task (see Bond and Taylor 2015;McDougle et al 2015;Taylor et al 2014). The visual display included numbered landmarks presented on the virtual ring (Fig.…”

“…The preceding discussion suggests that outcome-based feedback may not influence motor adaptation directly but, rather, influences other learning processes that operate during sensorimotor adaptation tasks such as operant conditioning (Shmuelof et al 2012) and explicit strategic aiming McDougle et al 2015;Taylor et al 2014;Taylor and Ivry 2011). Moreover, these other processes may have temporal constraints different from that associated with adaptation, allowing learning to occur under conditions with significant feedback delays.…”