Comparing motor imagery and verbal rehearsal strategies in children's ability to follow spoken instructions

Can Enactment and Motor Imagery Improve Working Memory for Instructions in Children with Autism Spectrum Disorder and Children with Intellectual Disability?

This study explored the impacts of enactment and motor imagery on working memory for instructions in children with autism spectrum disorder (ASD), children with intellectual disability (ID) and typically developing (TD) children. The participants were asked to hear (hearing condition), imagine enacting (motor imagery condition) and actually enact (enactment condition) instruction sequences and then recall them orally. Compared with the hearing condition, all groups performed better in the enactment condition, with the greatest advantage exhibited by the TD group; however, only the TD children performed better in the motor imagery condition. In summary, enactment has a weaker facilitating effect on ASD children and ID children than on TD children, and motor imagery is ineffective in the former two groups.

Exploring techniques for encoding spoken instructions in working memory: a comparison of verbal rehearsal, motor imagery, self-enactment and action observation

Encoding and recalling spoken instructions is subject to working memory capacity limits. Previous research suggests action-based encoding facilitates instruction recall, but has not directly compared benefits across different types of action-based techniques. The current study addressed this in two experiments with young adults. In Experiment 1, participants listened to instructional sequences containing four action-object pairs, and encoded these instructions using either a motor imagery or verbal rehearsal technique, followed by recall via oral repetition or enactment. Memory for instructions was better when participants used a motor imagery technique during encoding, and when recalling the instructions by enactment. The advantage of using a motor imagery technique was present in both verbal and enacted recall. In Experiment 2, participants encoded spoken instructions whilst implementing one of four techniques (verbal rehearsal, motor imagery, observation of others' actions or self-enactment), and then recalled the instructions by oral repetition or enactment. For both verbal and enacted recall, memory for instructions was least accurate in the rehearsal condition, while the other encoding conditions did not differ from each other. These novel findings indicate similar benefits of imagining, observation and execution of actions in encoding spoken instructions, and enrich current understanding of action-based benefits in working memory.

Improved motor imagery classification using adaptive spatial filters based on particle swarm optimization algorithm

Background

As a typical self-paced brain-computer interface (BCI) system, the motor imagery (MI) BCI has been widely applied in fields such as robot control, stroke rehabilitation, and assistance for patients with stroke or spinal cord injury. Many studies have focused on the traditional spatial filters obtained through the common spatial pattern (CSP) method. However, the CSP method can only obtain fixed spatial filters for specific input signals. In addition, the CSP method only focuses on the variance difference of two types of electroencephalogram (EEG) signals, so the decoding ability of EEG signals is limited.

Methods

To make up for these deficiencies, this study introduces a novel spatial filter-solving paradigm named adaptive spatial pattern (ASP), which aims to minimize the energy intra-class matrix and maximize the inter-class matrix of MI-EEG after spatial filtering. The filter bank adaptive and common spatial pattern (FBACSP), our proposed method for MI-EEG decoding, amalgamates ASP spatial filters with CSP features across multiple frequency bands. Through a dual-stage feature selection strategy, it employs the Particle Swarm Optimization algorithm for spatial filter optimization, surpassing traditional CSP approaches in MI classification. To streamline feature sets and enhance recognition efficiency, it first prunes CSP features in each frequency band using mutual information, followed by merging these with ASP features.

Results

Comparative experiments are conducted on two public datasets (2a and 2b) from BCI competition IV, which show the outstanding average recognition accuracy of FBACSP. The classification accuracy of the proposed method has reached 74.61 and 81.19% on datasets 2a and 2b, respectively. Compared with the baseline algorithm, filter bank common spatial pattern (FBCSP), the proposed algorithm improves by 11.44 and 7.11% on two datasets, respectively (p < 0.05).

Conclusion

It is demonstrated that FBACSP has a strong ability to decode MI-EEG. In addition, the analysis based on mutual information, t-SNE, and Shapley values further proves that ASP features have excellent decoding ability for MI-EEG signals and explains the improvement of classification performance by the introduction of ASP features. These findings may provide useful information to optimize EEG-based BCI systems and further improve the performance of non-invasive BCI.

The relationship between interactive-imagery instructions and association memory

Interactive imagery, one of the most effective strategies for remembering pairs of words, involves asking participants to form mental images during study. We tested the hypothesis that the visual image is, in fact, responsible for its memory benefit. Neither subjectively reported vividness (all experiments) nor objective imagery skill (experiments 1 and 3) could explain the benefit of interactive imagery for cued recall. Aphantasic participants, who self-identified little to no mental imagery, benefited from interactive-imagery instructions as much as controls (experiment 3). Imagery instructions did not improve memory for the constituent order of associations (AB versus BA), even when participants were told how to incorporate order within their images (experiments 1 and 2). Taken together, our results suggest that the visual format of images may not be responsible for the effectiveness of the interactive-imagery instruction and moreover, interactive imagery may not result in qualitatively different associative memories.

EXPRESS: Translating words into actions in working memory: the role of spatial-motoric coding

Research from a working memory perspective on the encoding and temporary maintenance of sequential instructions has established a consistent advantage for enacted over verbal recall. This is thought to reflect action planning for anticipated movements at the response phase. We describe five experiments investigating this, comparing verbal and enacted recall of a series of action–object pairings under different potentially disruptive concurrent task conditions, all requiring repetitive movements. A general advantage for enacted recall was observed across experiments, together with a tendency for concurrent action to impair sequence memory performance. The enacted recall advantage was reduced by concurrent action for both fine and gross concurrent movement with the degree of disruption influenced by both the complexity and the familiarity of the movement. The results are discussed in terms of an output buffer store of limited capacity capable of holding motoric plans for anticipated action.