Contextual interference in children with brain lesions: a pilot study investigating blocked vs. random practice order of an upper limb robotic exergame

Introduction Evidence about contextual interference in children with brain lesions when practising motor tasks is lacking. Our main objective was to evaluate the feasibility of a randomised controlled trial (RCT) comparing blocked with random practice order of an upper limb robotic exergame to improve reaching in children with neuromotor disorders with a pilot trial. Methods We recruited children with brain lesions and impaired upper limb functions who underwent a 3-week schedule that consisted of baseline assessments, intervention period (participants were randomised to a blocked or random order group), and follow-up assessment. We evaluated ten feasibility criteria, including the practicability of the inclusion/exclusion criteria, recruitment rate, feasibility of randomisation, scheduling procedure, and the participants’ programme adherence. Results The inclusion/exclusion criteria were not completely feasible as patients who were not able to perform the exergames were included. Twelve participants were recruited, and six datasets were used for analysis. The scheduling and randomisation procedures were generally feasible, but the procedure was only partially feasible for the participants, as some sessions were aborted due to lack of motivation and fatigue. Conclusion An RCT following this study protocol is not feasible. We formulated suggestions for future studies that aim to investigate contextual interference as in this pilot study. Trial registration ClinicalTrials.gov Identifier: NCT02443857, registered on May 14, 2015

A multi-representation approach to the contextual interference effect: effects of sequence length and practice

The present study investigated the long-term benefit of Random-Practice (RP) over Blocked-Practice (BP) within the contextual interference (CI) effect for motor learning. We addressed the extent to which motor sequence length and practice amount factors moderate the CI effect given that previous reports, often in applied research, have reported no long-term advantage from RP. Based on predictions arising from the Cognitive framework of Sequential Motor Behavior (C-SMB) and using the Discrete Sequence Production (DSP) task, two experiments were conducted to compare limited and extended practice amounts of 4- and 7-key sequences under RP and BP schedules. Twenty-four-hour delayed retention performance confirmed the C-SMB prediction that the CI-effect occurs only with short sequences that receive little practice. The benefit of RP with limited practice was associated with overnight motor memory consolidation. Further testing with single-stimulus as well as novel and unstructured (i.e., random) sequences indicated that limited practice under RP schedules enhances both reaction and chunking modes of sequence execution with the latter mode benefitting from the development of implicit and explicit forms of sequence representation. In the case of 7-key sequences, extended practice with RP and BP schedules provided for equivalent development of sequence representations. Higher explicit awareness of sequence structures was associated with faster completion of practiced but also of novel and unstructured sequences.

Null Effects of Different Amounts of Task Variation in Both Contextual Interference and Differential Learning Paradigms

Various motor learning approaches, such as Schema Theory, Contextual Interference or Differential Learning, have proposed that varying the task during skill acquisition prompts superior learning. However, past research has mainly compared task variation in an experimental group to no task variation in a control group. Past research has more rarely compared specific intervention groups and/or addressed how varying amounts of task variation may affect skill learning. Our aim in this study was to compare motor learning of golf putting across four groups of novice golfers randomly assigned to these conditions: (a) a contextual interference group who putted at varied putting distances and had varied repetitive weekly schedule patterns, (b) a differential learning group who putted at multiple putting distances, putting amplitudes, and putting movements and had no repetitions, (c) an identical differential learning as in (b) except that participants also varied the putter, and (d) a control group who experienced no practice variations. Participants were 42 university students randomly divided into the four groups. All groups completed eight training sessions of 36 putts per session over four weeks, a pretest, posttest, two retention tests (one and three weeks after posttest) and transfer tasks (different floor). Average hit ratios and minimal distances to the hole were captured and analyzed by Scheirer-Ray-Hare test and Mann-Whitney post-hoc tests. Results showed improved hit ratios from pre- to post-test for all groups, and a stable retention performance for the variable training groups in contrast to the control group ( p = .003). Transfer performance was low for all variable training groups with a significantly lower control group performance on transfer test 2 ( p = .008). In conclusion, variable training schedules in all experimental groups benefited motor learning relative to controls, and differences in the amount of task variation between groups with variable training schedules did not affect skill acquisition.

Prefrontal Cortex Activation During Motor Sequence Learning Under Interleaved and Repetitive Practice: A Two-Channel Near-Infrared Spectroscopy Study

Training under high interference conditions through interleaved practice (IP) results in performance suppression during training but enhances long-term performance relative to repetitive practice (RP) involving low interference. Previous neuroimaging work addressing this contextual interference effect of motor learning has relied heavily on the blood-oxygen-level-dependent (BOLD) response using functional magnetic resonance imaging (fMRI) methodology resulting in mixed reports of prefrontal cortex (PFC) recruitment under IP and RP conditions. We sought to clarify these equivocal findings by imaging bilateral PFC recruitment using functional near-infrared spectroscopy (fNIRS) while discrete key pressing sequences were trained under IP and RP schedules and subsequently tested following a 24-h delay. An advantage of fNIRS over the fMRI BOLD response is that the former measures oxygenated and deoxygenated hemoglobin changes independently allowing for assessment of cortical hemodynamics even when there is neurovascular decoupling. Despite slower sequence performance durations under IP, bilateral PFC oxygenated and deoxygenated hemoglobin values did not differ between practice conditions. During test, however, slower performance from those previously trained under RP coincided with hemispheric asymmetry in PFC recruitment. Specifically, following RP, test deoxygenated hemoglobin values were significantly lower in the right PFC. The present findings contrast with previous behavioral demonstrations of increased cognitive demand under IP to illustrate a more complex involvement of the PFC in the contextual interference effect. IP and RP incur similar levels of bilateral PFC recruitment, but the processes underlying the recruitment are dissimilar. PFC recruitment during IP supports action reconstruction and memory elaboration while RP relies on PFC recruitment to maintain task variation information in working memory from trial to trial. While PFC recruitment under RP serves to enhance immediate performance, it does not support long-term performance.

Backstroke to Breaststroke Turning Performance in Age-Group Swimmers: Hydrodynamic Characteristics and Pull-Out Strategy

We compared the hydrodynamic characteristics and pull-out strategies of four backstroke-to-breaststroke turning techniques in young swimmers. Eighteen 11 and 12-year-old swimmers participated in a 4 week intervention program including 16 contextual interference sessions. The hydrodynamic variables were assessed through inverse dynamics, and the pull-out strategy kinematics were assessed with tracking markers followed by 12 land cameras and 11 underwater cameras. Swimmers randomly completed sixteen 30 m maximal backstroke-to breaststroke-open, somersault, bucket and crossover turns (four in each technique) with a 3 min rest. The data showed higher drag force, cross-sectional area and drag coefficient values for the first (compared with the second) gliding position. The crossover turn revealed the highest push-off velocity (2.17 ± 0.05 m·s−1), and the somersault turn demonstrated the lowest foot plant index (0.68 ± 0.03; 68%), which could have affected the first gliding, transition and second gliding depths (0.73 ± 0.13, 0.86 ± 0.17 and 0.76 ± 0.17 m). The data revealed the consistency of the time spent (4.86 ± 0.98 s) and breakout distance (6.04 ± 0.94 m) among the four turning techniques, and no differences were observed between them regarding time and average velocity up to 7.5 m. The hydrodynamic characteristics and pull-out strategy of the backstroke-to-breaststroke turns performed by the age group swimmers were independent of the selected technique.

Effects of Contextual Interference on Learning of Falling Techniques

The main aim of this investigation was to determine the effect of high contextual interference (HCI) and low contextual interference (LCI) on motor learning of falling techniques. Thirty-five kinesiology students (21 males and 14 females; mean ± SD, age = 19.4 ± 0.69 years) were randomly assigned to the HCI or LCI practice group. The participants’ task was to learn two judo falling techniques on both sides over 3 weeks. The two-way analysis of variance found no difference between LCI and HCI in the performance at the pretest, posttest, retention, and transfer. Both groups improved posttest and retention performance. Finally, differences were found for both groups between the falling performance in the posttest and the application test (except for the right yoko ukemi fall in the HCI). Lower application test scores led to the conclusion that the 3-week treatment was insufficient to reach the application level of the falling techniques.

What Is the Level of Contextual Interference in Serial Practice? A Meta-Analytic Review

For over 40 years, the contextual interference effect in motor learning has been investigated. While the difference between levels of contextual interference experienced under blocked and random practice are well established, the difference in the levels of contextual interference experienced under serial and random practice is still ambiguous. Therefore, a meta-analytic review was conducted to clarify this inconsistency. We focused on one question: Do random practice and serial practice have the same effect on motor learning? ISI Web of Science, PubMed, and Scopus database were searched. Nine studies were included. The results of our meta-analyses show that serial and random practices present the same results in terms of performance in retention and transfer tests. This result is aligned to the original finding of the contextual interference effect, as well as its explanatory hypotheses. In addition, a complementary explanation in defense of the same mechanisms operating in serial and random practices is discussed. In conclusion, our results suggest that serial practice present high contextual interference.