The Effect of Perturbation Variability on Sensorimotor Adaptation Does Not Require an Implicit Memory of Errors

Abstract

In a recent paper entitled, An implicit memory of errors limits human sensorimotor adaptation, Albert and colleagues presented a model in which the adaptive response of the sensorimotor system is flexibly modulated by recent experience, or what they refer to as a memory of errors. This hypothesis stands in contrast to prevailing models in which automatic and implicit responses to movement errors are relatively insensitive to the statistical properties of the environment. A prime example of this rigidity is that the adaptation system exhibits a saturated response to large errors, resulting in a non-linear motor correction function, a feature that is independent of experience. Here we show that the key results reported in Albert et al. are fully explained by presupposing this rigid motor correction function without reference to memory-dependent changes in error sensitivity. As such, the evidence presented in Albert et. al. does not support the claim that the history of errors modulates implicit adaptation.

Contextual effects in sensorimotor adaptation adhere to associative learning rules

“…The COIN model suggests that spontaneous recovery, consistency effects and savings may emerge due to contextual inferences; these inferences likely involve cognitive systems related to executive function and nonmotor memory systems (Collins and McDougle, 2021). Consistent with this view, growing evidence show that these phenomena are, in large degree, the result of strategic changes (Haith et al, 2015;Morehead et al, 2015;Leow et al, 2020;Avraham et al, 2020Avraham et al, , 2021Wang et al, 2022).…”

Perturbation variance suppresses error sensitivity in the implicit learning system

“…We do not mean to suggest that the ideas presented by Wang et al 2 make no contribution at all to implicit behavior. Instead, we are more inclined to take a pluralistic view that the implicit system's error sensitivity is shaped not only by experience (Albert et al), but also by error magnitude (Wang et al).…”

“…In summary, the viewpoint proposed by Wang et al 2 can be directly tested in the data. The empirical error sensitivity and motor correction curves (Figs.…”

“…We observed that perturbation variability impaired implicit learning by downregulating its sensitivity to error. Recently, Wang et al 2 present an alternate viewpoint: implicit error sensitivity does not change with experience, only the errors observed by the implicit system change. Here we evaluated this alternate view by empirically measuring error sensitivity as a function of error size.…”

Understanding implicit sensorimotor adaptation as a process of proprioceptive re-alignment

“…Moreover, the attenuation of adaptation due to uncertainly can emerge from differential sampling of error space relative to a condition with low uncertainty ( Tsay et al, 2022c ), even when the learning rate is identical for the two conditions. Given the mixed results on this issue (also see: Hutter and Taylor, 2018 ; Wang et al, 2022 ), it is unclear if extrinsic variability contributes to the strength of the sensory prediction.…”