Dealing with Possible Baseline Inequalities Between Experimental Groups – The Case of Motor Learning

Abstract

One important concept of experimental design is the random assignment of participants to experimental groups. This randomization process is used to prevent selection bias, as well as to provide a strong basis for a cause-and-effect relationship between the independent variable/s and the dependent variable/s. In small sample sizes, simple randomization may not provide equal groups at baseline for one or more of the variables, and therefore more restricted types of randomization, such as the stratified permuted-block randomization, can be used. A code was written to calculate the probability that simple randomization will not lead to equality between groups at baseline, and then an example of stratified permuted-block randomization was examined. The findings suggest that for certain variables that are commonly measured in experiments in motor learning, there is a relatively high probability that groups will not be equal at baseline after simple randomization. This observation reflects the small sample sizes usually found in the literature on motor learning. However, stratified permuted-block randomization does lead to greater equality among groups. Implications for researchers are discussed, and a flowchart is proposed that will allow researchers to decide whether to use simple or stratified randomization.     

The intelligent reflex

ABSTRACT

The seeming distinction between motor and cognitive skills has hinged on the fact that the former are automatic and non-propositional (knowing-how), whereas the latter are slow and deliberative (knowing-that). Here, the physiological and behavioral phenomenon of long-latency stretch reflexes is used to show that “knowing-that” can be incorporated into “knowing-how,” either immediately or through learning. The experimental demonstration that slow computations can, with practice, be cached for fast retrieval, without the need for re-computation, dissolves the intellectualist/anti-intellectualist distinction: All complex human tasks, at any level of expertise, are a combination of intelligent reflexes and deliberative decisions.     

Sleep dependent consolidation of gross motor sequence learning with motor imagery

Acquisition of gross motor sequence learning with physical and mental training elicits gains in performance. However, the effects of sleep or daytime consolidation after both types of practice remain unclear, especially the effects upon the goal- and movement-based components of a gross motor sequential task. The main purpose of this study was to test the effect of physical practice (PP) and motor imagery practice (MIP) on the acquisition and consolidation processes of gross motor sequence learning.Seventy-six participants were tested before and after PP or MIP on a whole-body sequential paradigm, following either a night of sleep (PP_sleep and MIP_sleep groups) or an equivalent daytime period (PP_day and MIP_day groups). Control groups without training were tested following similar timespans (CTRL_sleep and CTRL_day groups). The number of sequential movements and the centre of mass displacement – corresponding to goal and movement-based components, respectively – were assessed.Results showed that relative to the CTRL groups, the PP and MIP groups improved performance during acquisition. Importantly, only the MIP_sleep group further improved performance after a night of sleep; participants of other groups stabilised their performance after consolidation. Additionally, the number of sequential movements and the centre of mass displacement evolved conjointly without being influenced by the type of training or the nature of the consolidation.To conclude, these results confirm that sleep contributes to the consolidation of gross motor sequence learning acquired with MIP but not PP. The relationship between the goal- and movement-based components of a gross motor sequential task is discussed.     

The effect of augmented feedback on the performance and learning of gross motor and sport-specific skills: A systematic review

BackgroundAugmented feedback is often provided by coaches and practitioners as a method to enhance the performance of athletes and learners. When implementing a feedback intervention, it is important to assess the expertise of the learner and the complexity of the skill, to ensure an appropriate feedback modality, frequency, and timing is provided. However, researchers have a limited understanding of how these variables interact to influence the performance and learning of gross motor and sport-specific skills.ObjectivesThe purpose of this systematic review was to examine the effects of augmented feedback on the performance and learning of gross motor and sport-specific skills in an adult population.MethodsA systematic literature search was conducted on electronic databases, PubMed, Web of Science and PsycINFO, from inception to March 2020, with a revised search completed to January 2022. The search terms used were related to augmented feedback and motor performance and learning. Studies were included if they consisted of a randomised control trial with pre- and retention-testing measures, which investigated an AF intervention on a gross motor and/or sport-specific skill in a healthy adult population. Risk of bias was assessed using the revised Cochrane risk-of-bias tool for randomised trials (RoB2).ResultsTwenty-four studies were included, with a total of 895 participants. Most studies reported a learning improvement following the provision of AF. One study documented a decrease in performance, and two studies reported no learning improvement Conflicting evidence was reported regarding which feedback frequency, timing, and duration was most appropriate. Furthermore, the inconsistency in methodological designs (control group types; timing of retention-tests; lack of retention tests) limited the comparisons that could be made between studies. Eighteen studies reported a high risk of bias, with the remaining six presenting some concerns.ConclusionAlthough studies have shown positive effects of AF on the performance and learning of gross motor and sport-specific skills, the majority are at a high risk of bias. Additionally, studies lacked standardisation in methodology, and results surrounding features of AF interventions were conflicting. Despite the conceptually sound rationale, further research is required to provide stronger evidence and a more robust understanding to better inform practitioners on how AF truly impacts the performance and learning of gross motor and sport-specific skills.RegistrationThis systematic review was registered on the Open Science Framework (https://osf.io/mrxzg) (10.17605/OSF.IO/MRXZG)     

五论以用户为中心的设计:从自动化到智能时代的自主化以及自动驾驶车

综述人因学在人-自动化交互、人-自主化(autonomy)交互以及人机组队(human-machine teaming)方面的研究,梳理了自动化与自主化的人因学特征和问题,通过建立一个自主化、自动化与人工干预三者之间关系的概念模型来表征自主化人因学的问题空间。总结了智能自主化技术所带来的新型人机合作关系,促使采用新的人因学研究和应用范式,重新评估现有的人因学理论、方法以及今后的研究。针对自主化技术的应用,分析当前自动驾驶车设计中的人因学问题。呼吁在自动驾驶车研发中要重视人因学问题,人因学要提供学科支持和完整的人因学解决方案。