Implicit Learning Research Articles

Differential Aging Effects on Implicit and Explicit Sensorimotor Learning.

Deterioration in motor control is a hallmark of aging, significantly contributing to a decline in quality of life. More controversial is the question of whether and how aging impacts sensorimotor learning. We hypothesized that the inconsistent picture observed in the current literature can be attributed to at least two factors. First, aging studies tend to be underpowered. Second, the learning assays used in these experiments tend to reflect, to varying degrees, the operation of multiple learning processes, making it difficult to make inferences across studies. We took a two-pronged approach to address these issues. We first performed a meta-analysis of the sensorimotor adaptation literature focusing on outcome measures that provide estimates of explicit and implicit components of adaptation. We then conducted two well-powered experiments to re-examine the effect of aging on sensorimotor adaptation, using behavioral tasks designed to isolate explicit and implicit processes. Convergently, both approaches revealed a striking dissociation: Older individuals exhibited a marked impairment in their ability to discover an explicit strategy to counteract a visuomotor perturbation. However, they exhibited enhanced implicit recalibration. We hypothesize that the effect of aging on explicit learning reflects an age-related decline in reasoning and problem solving, and the effect of aging on implicit learning reflects age-related changes in multisensory integration. Taken together, these findings deepen our understanding of the impact of aging on sensorimotor learning.

Transcranial Direct Current Stimulation (tDCS) on Soccer Players: A Mini-Review

Background: This mini-review explores the application of Transcranial Direct Current Stimulation (tDCS) in enhancing cognitive and motor performance in soccer players. This review synthesizes findings from recent studies focusing on tDCS’s impact on the primary Motor Cortex (M1) and the Dorsolateral Prefrontal Cortex (dlPFC). Results: studies conducted to date show that tDCS can enhance muscle strength, reduce perceived fatigue, and improve well-being in soccer players. For instance, anodal tDCS applied to the primary motor cortex has been shown to temporarily increase quadriceps strength, while stimulation of the dlPFC has improved recovery post-match and enhanced cognitive functions like reaction time and implicit motor learning. Conclusion: the mini-review highlights the need for more targeted research, emphasizing the importance of individualized protocols and advanced neuroimaging techniques to better understand tDCS’s mechanisms and optimize its use in sports. Future directions suggest adopting neurocircuit-based strategies such as RDoC to tailor interventions more precisely to athletes’ needs. This integration could potentially maximize the benefits of tDCS, offering a holistic approach to enhancing athletic performance and recovery in soccer players.

Explicit and implicit locomotor learning in individuals with chronic hemiparetic stroke.

Motor learning involves both explicit and implicit processes that are fundamental for acquiring and adapting complex motor skills. However, stroke may damage the neural substrates underlying explicit and/or implicit learning, leading to deficits in overall motor performance. While both learning processes are typically used in concert in daily life and rehabilitation, no gait studies have determined how these processes function together after stroke when tested during a task that elicits dissociable contributions from both. Here, we compared explicit and implicit locomotor learning in individuals with chronic stroke to age- and sex-matched neurologically intact controls. We assessed implicit learning using split-belt adaptation (where two treadmill belts move at different speeds). We assessed explicit learning (i.e., strategy-use) using visual feedback during split-belt walking to help individuals explicitly correct for step length errors created by the split-belts. The removal of visual feedback after the first 40 strides of split-belt walking, combined with task instructions, minimized contributions from explicit learning for the remainder of the task. We utilized a multi-rate state-space model to characterize individual explicit and implicit process contributions to overall behavioral change. The computational and behavioral analyses revealed that, compared to controls, individuals with chronic stroke demonstrated deficits in both explicit and implicit contributions to locomotor learning, a result that runs counter to prior work testing each process individually during gait. Since post-stroke locomotor rehabilitation involves interventions that rely on both explicit and implicit motor learning, future work should determine how locomotor rehabilitation interventions can be structured to optimize overall motor learning.

Top-down and bottom-up oscillatory dynamics regulate implicit visuomotor sequence learning.

Implicit visuomotor sequence learning is crucial for acquiring skills that result in automated behaviors. The oscillatory dynamics underpinning this learning process are not well understood. To address this gap, the current study employed electroencephalography with a medium-density array (64 electrodes) to investigate oscillatory activity associated with implicit visuomotor sequence learning in the Serial Reaction Time task. In the task, participants unknowingly learn a series of finger movements. Eighty-five healthy adults participated in the study. Analyses revealed that theta activity at the vertex and alpha/beta activity over the motor areas decreased over the course of learning. No associations between alpha/beta and theta power were observed. These findings are interpreted within a dual-process framework: midline theta activity is posited to regulate top-down attentional processes, whereas beta activity from motor areas underlies the bottom-up encoding of sensory information from movement. From this model, we suggest that during implicit visuomotor sequence learning, top-down processes become disengaged (indicated by a reduction in theta activity), and modality specific bottom-up processes encode the motor sequence (indicated by a reduction in alpha/beta activity).

Limb-related sensory prediction errors and task-related performance errors facilitate human sensorimotor learning through separate mechanisms.

The unpredictable nature of our world can introduce a variety of errors in our actions, including sensory prediction errors (SPEs) and task performance errors (TPEs). SPEs arise when our existing internal models of limb-environment properties and interactions become miscalibrated due to changes in the environment, while TPEs occur when environmental perturbations hinder achievement of task goals. The precise mechanisms employed by the sensorimotor system to learn from such limb- and task-related errors and improve future performance are not comprehensively understood. To gain insight into these mechanisms, we performed a series of learning experiments wherein the location and size of a reach target were varied, the visual feedback of the motion was perturbed in different ways, and instructions were carefully manipulated. Our findings indicate that the mechanisms employed to compensate SPEs and TPEs are dissociable. Specifically, our results fail to support theories that suggest that TPEs trigger implicit refinement of reach plans or that their occurrence automatically modulates SPE-mediated learning. Rather, TPEs drive improved action selection, that is, the selection of verbally sensitive, volitional strategies that reduce future errors. Moreover, we find that exposure to SPEs is necessary and sufficient to trigger implicit recalibration. When SPE-mediated implicit learning and TPE-driven improved action selection combine, performance gains are larger. However, when actions are always successful and strategies are not employed, refinement in behavior is smaller. Flexibly weighting strategic action selection and implicit recalibration could thus be a way of controlling how much, and how quickly, we learn from errors.

Implicit Versus Explicit Learning a Novel Skill for High School Students

The aim of the study was to compare the effects of implicit learning using dual task-paradigm, with explicit learning on learning a novel skill, and if the performance is maintained over a prolonged period of time. Twenty-six high school adolescents (n = 26, boys n = 15, girls n = 11, age: 16 ± 0.66 years) performed a four-week front-flip learning program, where participants underwent two hours front flip practice in total between the pre- and post-test session followed by two tests; three and six months after the post-test, in which the front-flip was not practiced. Performance was evaluated by two independent gymnastics judges. Both groups increased performance at the post test, with significantly higher scores in the explicit group compared with the implicit group. Probably benefiting from error correction to select positive action outcomes and avoid negative ones consciously. However, the explicit group was also the only group that significantly decreased performance again at first retention test, suggesting that their reliance on the retrieval of declarative knowledge from working memory was subject to decay. While it seems that performance learned via implicit learning may deteriorate more slowly, but also continuously throughout six months suggesting that the directly accumulated procedural knowledge may need for proper reinforcement and practice.

A kinematically complex multi-articular motor skill for investigating implicit motor learning.

Here we present a task developed to probe implicit learning of a complex motor skill. This task addresses limitations related to task complexity noted in the literature for methods investigating implicit motor learning, namely the serial reaction time task and continuous tracking task. Specifically, the serial reaction time task is limited by the kinematic simplicity of the required movement and the continuous tracing task faces time-on-task confounds and limitations in the control of task difficulty. The task presented herein addresses these issues by employing a kinematically complex multi-articular movement that controls factors that contribute to task difficulty: stimulus animation velocity and trajectory complexity. Accordingly, our objective was to validate the use of this task in probing implicit motor learning, hypothesizing that participants would learn one of the repeating stimuli implicitly. Participants engaged in six blocks of training whereby they first observed and then reproduced a seemingly random complex trajectory. Repeated trajectories were embedded amongst random trajectories. In line with the hypothesis, error for the repeated trajectories was decreased in comparison to that observed for the random trajectories and 73% of participants were unable to identify one of the repeated trajectories, demonstrating the occurrence of implicit learning. While the task requires minor alteration to optimize learning, ultimately the findings underline the task's potential to investigate implicit learning of a complex motor skill.

Humans flexibly use visual priors to optimize their haptic exploratory behavior

Humans can use prior information to optimize their haptic exploratory behavior. Here, we investigated the usage of visual priors, which mechanisms enable their usage, and how the usage is affected by information quality. Participants explored different grating textures and discriminated their spatial frequency. Visual priors on texture orientation were given each trial, with qualities randomly varying from high to no informational value. Adjustments of initial exploratory movement direction orthogonal to the textures’ orientation served as an indicator of prior usage. Participants indeed used visual priors; the more so the higher the priors’ quality (Experiment 1). Higher task demands did not increase the direct usage of visual priors (Experiment 2), but possibly fostered the establishment of adjustment behavior. In Experiment 3, we decreased the proportion of high-quality priors presented during the session, hereby reducing the contingency between high-quality priors and haptic information. In consequence, even priors of high quality ceased to evoke movement adjustments. We conclude that the establishment of adjustment behavior results from a rather implicit contingency learning. Overall, it became evident that humans can autonomously learn to use rather abstract visual priors to optimize haptic exploration, with the learning process and direct usage substantially depending on the priors’ quality.

Effectiveness of Detailed Information on Subconscious Motor Sequence Learning in Acute Stroke

Introduction: Stroke is defined as a rapidly developing clinical sign of focal disturbance of central function of presumed vascular origin & of more than 24-hours duration1. Clinically a variety of deficits are possible including changes in the level of consciousness & impairment of sensory, motor, cognitive , perceptual & language functions2. Although it is unequivocal that the extremities contra lateral to the unilateral cerebral lesion are more affected than the ipsilesional extremities, there is now a large body of research that suggests that the ipsilesional extremities are not normal often clinically assumed as “the non affected side” ,particular to the upper extremity there is increasing evidence of sensory-motor control deficits on the ipsilesional side3. These ipsilesional deficits may reflect motor control deficits that are masked on the contralateral side by hemiplegia and hemisensory loss3. The non-dominant hemisphere plays a primary role in the function of complex visuo-spatial accuracy, whereas the dominant hemisphere is mainly involved in the motor control of bilateral upper limbs as well as the performance of complex tasks. Although the cause of ipsilesional movement abnormalties have not been elucidated accurately, several possible mechanisms have been suggested i.e. the injury of the uncrossed corticospinal system, inhibitory transcallosal influence on the unaffected hemisphere, the different roles of side-to-side hemispheric function depending on the specific properties of the task & bilateral hemispheric processing for high cognitive activity4. In persons with stroke, deficits in targeted movements, compared with comparison groups, have been identified in the ipsilateral extremities, even when clinical measures of the upper extremities reveal little or no deficit5 Objective: To study effectiveness of detailed information on subconscious motor sequence learning in acute stroke Research Design: Observational design Methodology: A total of 22 subjects with anterior circulation stroke (diagnosed by neurologist) were included in the study. In the group A (No-Explicit Information group) 13 subjects were recruited (total 15 subjects were recruited, but 2 patients left in between). In the group B (Explicit Information Group) 9 subjects were recruited. Result: Descriptive statistics is used to analyze subject characteristics. 22 subjects recruited for the study were randomly assigned to each group, group A (Non EI) with 9 males and 4 females with mean age of 59.94 years and mean score on MMSE, & COVS, were 27.92 and 6.00. Group B (EI) with 8 males and 1 female with mean age of 58.22 years and mean score on MMSE, & COVS were 29.00 and 6.56.On comparing the Age (p=0.75), MMSE score (p=0.09), and COVS score (p=0.08) between the two groups, the results were not significant (at p<0.05). Thus both the groups are comparable. Conclusion: Our findings suggest that explicit information when given prior to physical practice improved implicit motor sequence learning in subjects with acute stroke; however subjects were not able to express it explicitly. Keywords: non-dominant hemisphere, Stroke, disability, uncrossed corticospinal, explicit and implicit learning

Grammar Learning Methods and Grammar Learning Strategies: Are They Related?

This study responds to numerous calls for research on Grammar Learning Strategies (GLS), an area that has been neglected for years. The research sheds light on the relationship between grammar learning or instructional approaches and students' utilization of GLS assigned to develop explicit and implicit knowledge of grammar. Two sub-categories of Pawlak's (2018) Grammar Learning Strategy Inventory (GLSI) were employed to assess GLS use in these two sub-categories by students who prefer explicit grammar learning and those who prefer implicit grammar learning. A Pearson correlation coefficient test was conducted to examine this relationship. The study revealed a moderate use of GLS for developing explicit and implicit grammar knowledge. Furthermore, it found an insignificant, fragile, and negative correlation between grammar learning or instructional approaches and GLS used to develop explicit knowledge of grammar. Similarly, an insignificant, very weak, and negative correlation was reported between grammar learning or instructional approaches, and GLS used to develop implicit knowledge of grammar. The study discusses factors influencing language learning and GLS use and highlights the limitations.

KaTaGCN: Knowledge-Augmented and Time-Aware Graph Convolutional Network for efficient traffic forecasting

Dynamic spatio-temporal dependencies and temporal patterns in traffic series are critical factors affecting traffic forecasting accuracy. Due to the intrinsic challenges of incorporating explicit, logical knowledge into the implicit black-box learning process of neural networks, only a few methods effectively use prior knowledge to improve the learning of traffic forecasting. To tackle this problem, we introduce a new approach called Knowledge-augmented and Time-aware Graph Convolutional Network, namely KaTaGCN. At its core, we have created a knowledge-augmented module that boosts the diffusion weights between closely related adjacent nodes in graph learning. This is achieved by implementing a new loss function. Then, to learn the periodic implicit relationship between these timestamps and traffic signals, the weights and biases are chosen adaptively to be trained based on the timestamps of each sample. Finally, a gated spatio-temporal mapping module regresses high-dimensional embedded features from spatial and temporal dimensions. KaTaGCN is structured without any attention mechanisms or recurrent neural networks. Extensive experimental results on six real-world public traffic datasets demonstrate that KaTaGCN achieves an average improvement of 4.29% in forecasting performance compared with suboptimal results.

Looking beyond literacy and phonology: word learning and phonological cue use in children with and without dyslexia

IntroductionThis study investigated whether children with and without dyslexia differ in word learning and whether phonological cues to word class play a role. If children with dyslexia have difficulties with implicit learning, they might be less sensitive to such cues.MethodsA group of 89 Dutch primary school children from Grades 3 to 6 participated in a word learning experiment, consisting of children with dyslexia (n = 44) and typically developing children (n = 45). Test items were four monosyllabic ‘verb-like' nonwords (e.g., voek) and four bisyllabic ‘noun-like' nonwords (e.g., banijn). They were presented as novel verbs or nouns in a two word sentence frame (e.g., “I voek” or “a voek”), paired with pictures of unfamiliar actions or objects. Nonwords were either consistent (e.g., “I voek,” “a banijn”) or inconsistent (e.g., “I banijn,” “a voek”) with word class. The word learning experiment consisted of a repetition, identification, and naming phase.ResultsChildren with dyslexia showed lower word learning outcomes in the naming phase. However, phonological cues did not affect word learning in either group. Regression analyses indicated that phoneme awareness, receptive vocabulary, and nonword reading were predictors of word learning for all children.DiscussionThese findings indicate that Dutch children with dyslexia have more difficulty in recalling novel words, fitting in with their phonological difficulties. Phonological cues to word class did not contribute to word learning in either group.

Distributional Learning and Overnight Consolidation of Nonnative Tonal Contrasts by Tonal Language Speakers.

Previous studies have reported the success of distributional learning for adult speakers across segmental and suprasegmental categories immediately after training. On the other hand, second language (L2) perception models posit that the ease with which learners perceive a nonnative speech contrast depends on the perceptual mapping between the contrast and learners' first language (L1) categories. This study examined whether a difference in perceptual mapping patterns for different L2-Mandarin tonal contrasts might result in a difference in distributional learning effectiveness for tonal speakers and whether an interval of sleep enhanced the knowledge through consolidation. Following a pretest-training-posttest design, 66 L1-Cantonese participants with fewer than 9 years of Mandarin training were assigned to either the bimodal or unimodal distribution conditions. The participants of each group were asked to discriminate Mandarin level-falling (T1-T4) and level-rising (T1-T2) tone pairs on novel syllables in a within-subject design. All participants were trained in the evening, tested after training, and returned after 12 hr for overnight consolidation assessment. A significant distributional learning effect was observed for Mandarin T1-T4, but only after sleep. No significant distributional learning effect was observed for Mandarin T1-T2, either after training or after sleep. The findings may imply that distributional learning is contingent on perceptual mapping patterns of the target contrasts and that sleep may play a role in the consolidation of knowledge in an implicit statistical learning paradigm. https://doi.org/10.23641/asha.25970008.

Fairer AI in ophthalmology via implicit fairness learning for mitigating sexism and ageism

The transformative role of artificial intelligence (AI) in various fields highlights the need for it to be both accurate and fair. Biased medical AI systems pose significant potential risks to achieving fair and equitable healthcare. Here, we show an implicit fairness learning approach to build a fairer ophthalmology AI (called FairerOPTH) that mitigates sex (biological attribute) and age biases in AI diagnosis of eye diseases. Specifically, FairerOPTH incorporates the causal relationship between fundus features and eye diseases, which is relatively independent of sensitive attributes such as race, sex, and age. We demonstrate on a large and diverse collected dataset that FairerOPTH significantly outperforms several state-of-the-art approaches in terms of diagnostic accuracy and fairness for 38 eye diseases in ultra-widefield imaging and 16 eye diseases in narrow-angle imaging. This work demonstrates the significant potential of implicit fairness learning in promoting equitable treatment for patients regardless of their sex or age.

Error-based Implicit Learning in Language: The Effect of Sentence Context and Constraint in a Repetition Paradigm.

Prediction errors drive implicit learning in language, but the specific mechanisms underlying these effects remain debated. This issue was addressed in an EEG study manipulating the context of a repeated unpredictable word (repetition of the complete sentence or repetition of the word in a new sentence context) and sentence constraint. For the manipulation of sentence constraint, unexpected words were presented either in high-constraint (eliciting a precise prediction) or low-constraint sentences (not eliciting any specific prediction). Repetition-induced reduction of N400 amplitudes and of power in the alpha/beta frequency band was larger for words repeated with their sentence context as compared with words repeated in a new low-constraint context, suggesting that implicit learning happens not only at the level of individual items but additionally improves sentence-based predictions. These processing benefits for repeated sentences did not differ between constraint conditions, suggesting that sentence-based prediction update might be proportional to the amount of unpredicted semantic information, rather than to the precision of the prediction that was violated. In addition, the consequences of high-constraint prediction violations, as reflected in a frontal positivity and increased theta band power, were reduced with repetition. Overall, our findings suggest a powerful and specific adaptation mechanism that allows the language system to quickly adapt its predictions when unexpected semantic information is processed, irrespective of sentence constraint, and to reduce potential costs of strong predictions that were violated.

Implicit and Explicit Language Learning to Facilitate Subordinating Conjunction in Developmental Language Disorders

Abstract Background: Priming and recast approaches are scientifically proven to improve grammatical production abilities. However, based on a literature review, there are no articles that test the effectiveness of the priming and recast approach in improving grammatical skills such as subordinating conjunctions. Objective: This study aims to examine the effectiveness of the priming and recast approach in improving subordinating conjunctions in children with developmental language disorders. Objectives: This study aims to see the effectiveness of the priming and recast approach in improving subordinating conjunctions in children with developmental language disorders. Methods: This research uses a quasi-experiment, with multiple baseline across behaviors design. This research involved two children diagnosed with developmental language disorders aged 5 years. Each participant was trained to use subordinating conjunctions for five sessions, 30 minutes per session Results: In general, the priming and recast approach can improve the ability of subordinating conjunctions in children with developmental language disorders. Conclusion: Grammatical production of subordinating conjunctions can be trained using implicit or explicit learning. Keywords : priming, recast approach, language disorder, speech therapy, subordinating conjunctions

Exploring brain plasticity in developmental dyslexia through implicit sequence learning.

Developmental dyslexia (DD) is defined as difficulties in learning to read even with normal intelligence and adequate educational guidance. Deficits in implicit sequence learning (ISL) abilities have been reported in children with DD. We investigated brain plasticity in a group of 17 children with DD, compared with 18 typically developing (TD) children, after two sessions of training on a serial reaction time (SRT) task with a 24-h interval. Our outcome measures for the task were: a sequence-specific implicit learning measure (ISL), entailing implicit recognition and learning of sequential associations; and a general visuomotor skill learning measure (GSL). Gray matter volume (GMV) increased, and white matter volume (WMV) decreased from day 1 to day 2 in cerebellar areas regardless of group. A moderating effect of group was found on the correlation between WMV underlying the left precentral gyrus at day 2 and the change in ISL performance, suggesting the use of different underlying learning mechanisms in DD and TD children during the ISL task. Moreover, DD had larger WMV in the posterior thalamic radiation compared with TD, supporting previous reports of atypical development of this structure in DD. Further studies with larger sample sizes are warranted to validate these results.

Attenuation of implicit motor learning with consecutive exposure to visual errors

Visual errors induced by movement drive implicit corrections of that movement. When similar errors are experienced consecutively, does sensitivity to the error remain consistent each time? This study aimed to investigate the modulation of implicit error sensitivity through continuous exposure to the same errors. In the reaching task using visual error-clamp feedback, participants were presented with the same error in direction and magnitude for four consecutive trials. We found that implicit error sensitivity decreased after exposure to the second error. These results indicate that when visual errors occur consecutively, the sensorimotor system exhibits different responses, even for identical errors. The continuity of errors may be a factor that modulates error sensitivity.

Do Implicit Learning Deficit and Dyslexia Go Together? An fMRI and Behavioral Study

AbstractWhat is the relationship between literacy skills and implicit learning? To address previous mixed findings, we compared school‐aged readers, typical (CON, n = 54) and with dyslexia (DYS, n = 53), in relation to their performance on a serial reaction time task. For the first time, we also included an isolated spelling deficit group (ISD, n = 30) to control for distinctive effects of reading and spelling deficits. A linear reaction times analysis did not reveal between‐group differences in implicit learning. However, further examination revealed that most CON (65%) and ISD (63%) were implicit learners, whereas most DYS were nonlearners (64%). Brain activity showed differences in early learning phases: CON learners and DYS nonlearners activated the left inferior frontal gyrus (IFG) and left insula more than other groups. Our findings imply that implicit learning is more frequently disrupted in children with dyslexia than in typical readers, and that activation of the left IFG and insula contributes to effective learning in the latter group but it does not in the former.

Reward actively engages both implicit and explicit components in dual force field adaptation.

Motor learning occurs through multiple mechanisms, including unsupervised, supervised (error based), and reinforcement (reward based) learning. Although studies have shown that reward leads to an overall better motor adaptation, the specific processes by which reward influences adaptation are still unclear. Here, we examine how the presence of reward affects dual adaptation to novel dynamics and distinguish its influence on implicit and explicit learning. Participants adapted to two opposing force fields in an adaptation/deadaptation/error-clamp paradigm, where five levels of reward (a score and a digital face) were provided as participants reduced their lateral error. Both reward and control (no reward provided) groups simultaneously adapted to both opposing force fields, exhibiting a similar final level of adaptation, which was primarily implicit. Triple-rate models fit to the adaptation process found higher learning rates in the fast and slow processes and a slightly increased fast retention rate for the reward group. Whereas differences in the slow learning rate were only driven by implicit learning, the large difference in the fast learning rate was mainly explicit. Overall, we confirm previous work showing that reward increases learning rates, extending this to dual-adaptation experiments and demonstrating that reward influences both implicit and explicit adaptation. Specifically, we show that reward acts primarily explicitly on the fast learning rate and implicitly on the slow learning rates.NEW & NOTEWORTHY Here we show that rewarding participants' performance during dual force field adaptation primarily affects the initial rate of learning and the early timescales of adaptation, with little effect on the final adaptation level. However, reward affects both explicit and implicit components of adaptation. Whereas the learning rate of the slow process is increased implicitly, the fast learning and retention rates are increased through both implicit components and the use of explicit strategies.