Implicit and explicit learning in reactive and voluntary saccade adaptation

Abstract

Saccades can either be elicited automatically by salient peripheral stimuli or can additionally depend on explicit cognitive goals. Similarly, it is thought that motor adaptation is driven by the combination of a more automatic, implicit process and a more explicit, cognitive process. However, the degree to which such implicit and explicit learning contribute to the adaptation of more reactive and voluntary saccades remains elusive. To study this question, we employed a global saccadic adaptation paradigm with both increasing and decreasing saccade amplitudes. We assessed the resulting adaptation using a dual state model of motor adaptation. This model decomposes learning into a fast and slow process, which are thought to constitute explicit and implicit learning, respectively. Our results show that adaptation of reactive saccades is equally driven by fast and slow learning, while fast learning is nearly absent when adapting voluntary (i.e. scanning) saccades. This pattern of results was present both when saccade gain was increased or decreased. Our results suggest that the increased cognitive demands associated with voluntary compared to reactive saccade planning interfere specifically with explicit learning.

Implicit motor learning within three trials

“…An established convention of motor learning asserts that automatic or implicit components of learning emerge later in training following an initial more explicit or declarative stage, even for skill-maintenance tasks, like adaptation 1 – 6 . Perturbations in reach, saccade and locomotion adaptation evoke relatively quick adjustments to behaviour 4 , 6 – 12 , and some work has attempted to either infer implicit learning based on the assumption that implicit and explicit adaptation simply add to produce behavior 13 or measure it in paradigms that require explicitly suppressing natural responses to visual feedback 11 , 12 . However, it has not been directly measured how quickly implicit changes emerge.…”

Implicit motor learning within three trials

“…Two main implicit changes involved in adaptation, that rely on sensory-prediction error-based learning, are updates in internal models as well as the resulting changes in our state estimates (6)(7)(8). While perturbations in reach, saccade and locomotion adaptation evoke relatively quick adjustments to behaviour (4,(9)(10)(11)(12), it has not been directly measured how quickly implicit changes emerge.…”

“…An established convention of motor learning asserts that automatic or implicit components of learning emerge later in training following an initial more explicit or declarative stage, even for skillmaintenance tasks, like adaptation [1][2][3][4][5][6] . Perturbations in reach, saccade and locomotion adaptation evoke relatively quick adjustments to behaviour 4,[6][7][8][9][10][11][12] , and some work has attempted to either infer implicit learning based on the assumption that implicit and explicit adaptation simply add to produce behavior 13 or measure it in paradigms that require explicitly suppressing natural responses to visual feedback 11,12 . However, it has not been directly measured how quickly implicit changes emerge.…”

Transcranial Direct-Current Stimulation Does Not Affect Implicit Sensorimotor Adaptation: A Randomized Sham-Controlled Trial

“…Though sensorimotor adaptation was traditionally viewed as a testbed for examining procedural learning, recent studies have shown that various adaptation paradigms involve both explicit and implicit learning. Besides the visuomotor rotation investigated here, reaching adaptation with force field [ 52 ] or prism goggles [ 53 ], walking adaptation with a split-belt [ 54 ], and saccadic adaptation with a target jump [ 55 ] all involve cognitive components and strategic corrections to the perturbation. Taking force field adaptation as an example, people rely on proprioceptive feedback to adapt to a novel mechanical environment and have difficulty verbalizing their adaptation solution.…”