The Impact of Language Opacity and Proficiency on Reading Strategies in Bilinguals: An Eye Movement Study

Reading strategies vary across languages according to orthographic depth - the complexity of the grapheme in relation to phoneme conversion rules - notably at the level of eye movement patterns. We recently demonstrated that a group of early bilinguals, who learned both languages equally under the age of seven, presented a first fixation location (FFL) closer to the beginning of words when reading in German as compared with French. Since German is known to be orthographically more transparent than French, this suggested that different strategies were being engaged depending on the orthographic depth of the used language. Opaque languages induce a global reading strategy, and transparent languages force a local/serial strategy. Thus, pseudo-words were processed using a local strategy in both languages, suggesting that the link between word forms and their lexical representation may also play a role in selecting a specific strategy. In order to test whether corresponding effects appear in late bilinguals with low proficiency in their second language (L2), we present a new study in which we recorded eye movements while two groups of late German-French and French-German bilinguals read aloud isolated French and German words and pseudo-words. Since, a transparent reading strategy is local and serial, with a high number of fixations per stimuli, and the level of the bilingual participants' L2 is low, the impact of language opacity should be observed in L1. We therefore predicted a global reading strategy if the bilinguals' L1 was French (FFL close to the middle of the stimuli with fewer fixations per stimuli) and a local and serial reading strategy if it was German. Thus, the L2 of each group, as well as pseudo-words, should also require a local and serial reading strategy. Our results confirmed these hypotheses, suggesting that global word processing is only achieved by bilinguals with an opaque L1 when reading in an opaque language; the low level in the L2 gives way to a local and serial reading strategy. These findings stress the fact that reading behavior is influenced not only by the linguistic mode but also by top-down factors, such as readers' proficiency

Virtual Reality Environments and Haptic Strategies to Enhance Implicit Learning and Motivation in Robot-Assisted Training

Motivation plays a crucial role in motor learning and neurorehabilitation. Participants’ motivation could decline to a point where they may stop training when facing a very difficult task. Conversely, participants may perform well and consider the training boring if the task is too easy. In this paper, we present a combination of a virtual reality environment with different robotic training strategies that modify task functional difficulty to enhance participants’ motivation. We employed a pneumatically driven robotic stepper as a haptic interface. We first evaluated the use of disturbance observers as acceleration controllers to provide high robustness to varying system parameters, unmodeled dynamics and unknown disturbances associated with pneumatic control. The locomotor task to be learned in the virtual reality environment consisted of steering a recumbent bike to follow a desired path by changing the movement frequency of the dominant leg. The motor task was specially designed to engage implicit learning –i.e., learning without conscious recognition of what is learned. A haptic assistance strategy was developed in order to reduce the task functional difficulty during practice. In a feasibility study with eight healthy participants, we found that the haptic assistance provided by the robotic device successfully contributed to improve task performance during training, especially for less skilled participants. Furthermore, we found a negative correlation between participants’ motivation and performance error when training with haptic assistance, suggesting that haptic assistance has a great potential to enhance motivation during motor training

Effect of immersive visualization technologies on cognitive load, motivation, usability, and embodiment

Virtual reality (VR) is a promising tool to promote motor (re)learning in healthy users and brain-injured patients. However, in current VR-based motor training, movements of the users performed in a three-dimensional space are usually visualized on computer screens, televisions, or projection systems, which lack depth cues (2D screen), and thus, display information using only monocular depth cues. The reduced depth cues and the visuospatial transformation from the movements performed in a three-dimensional space to their two-dimensional indirect visualization on the 2D screen may add cognitive load, reducing VR usability, especially in users suffering from cognitive impairments. These 2D screens might further reduce the learning outcomes if they limit users’ motivation and embodiment, factors previously associated with better motor performance. The goal of this study was to evaluate the potential benefits of more immersive technologies using head-mounted displays (HMDs). As a first step towards potential clinical implementation, we ran an experiment with 20 healthy participants who simultaneously performed a 3D motor reaching and a cognitive counting task using: (1) (immersive) VR (IVR) HMD, (2) augmented reality (AR) HMD, and (3) computer screen (2D screen). In a previous analysis, we reported improved movement quality when movements were visualized with IVR than with a 2D screen. Here, we present results from the analysis of questionnaires to evaluate whether the visualization technology impacted users’ cognitive load, motivation, technology usability, and embodiment. Reports on cognitive load did not differ across visualization technologies. However, IVR was more motivating and usable than AR and the 2D screen. Both IVR and AR rea ched higher embodiment level than the 2D screen. Our results support our previous finding that IVR HMDs seem to be more suitable than the common 2D screens employed in VR-based therapy when training 3D movements. For AR, it is still unknown whether the absence of benefit over the 2D screen is due to the visualization technology per se or to technical limitations specific to the device

High-frequency transcutaneous cervical electrical stimulation: A pilot study

Early results suggest that transcutaneous stimulation of cervical regions may have a positive effect on recovery of upper limb motor function after neurological injuries. However, in clinical applications, patients find transcutaneous low-frequency spinal cord stimulation (LF-tSCS) unpleasant. Transcutaneous high-frequency spinal cord stimulation (HF-tSCS) has been presented as an option to reduce pain and discomfort produced by LF-tSCS. We performed a pilot study with 3 participants to compare the effects of HF-tSCS and LF-tSCS on upper limb reflex responses and reported pain level and discomfort. In the first part of the experiment, high- (i.e., monophasic and biphasic burst) vs low-frequency (i.e., monophasic pulse) single waveform cervical tSCS was applied and motor response threshold identified via electromyography (EMG). In the second part of the experiment, the three waveforms were administered as train pulses and the stimulation intensity was increased in four steps from 20% to 80% of the individual motor response threshold. Participants indicated the pain level for each stimulation intensity increment and waveform. We find that participants reported stronger discomfort in HF-tSCS than LF-tSCS stimulation at motor threshold level. Further, stimulation at subthreshold level was associated with strong discomfort in HF- and LF-tSCS train pulses, especially in participants with relatively high motor response threshold. We conclude that cervical HF-tSCS may not (yet) be an option for clinical application, even though acceptability may depend on the individual motor response threshold of the patient

Multi-purpose Robotic Training Strategies for Neurorehabilitation with Model Predictive Controllers

One of the main challenges in robotic neurorehabilitation is to understand how robots should physically interact with trainees to optimize motor leaning. There is evidence that motor exploration (i.e., the active exploration of new motor tasks) is crucial to boost motor learning. Furthermore, effectiveness of a robotic training strategy depends on several factors, such as task type and trainee’s skill level. We propose that Model Predictive Controllers (MPC) can satisfy many training/trainee’s needs simultaneously, while providing a safe environment without restricting trainees to a fixed trajectory. We designed two nonlinear MPCs to support training of a rich dynamic task (a pendulum task) with a delta robot. These MPCs differ from each other in terms of the application point of the intervention force: (i) to the virtual pendulum mass, and (ii) the virtual rod holding point, which corresponds to the robot end-effector. The effect of the MPCs on task performance, physical effort, motivation and sense of agency was evaluated in fourteen healthy participants. We found that the location of the applied controller force affects the task performance –i.e., the MPC that actuates on the pendulum mass significantly reduced performance errors and sense of agency during training, while the other MPC did not, probably due to low force saturation limits and slow optimization speed of the solver. Participants applied significantly more forces when training with the MPC that actuates on the pendulum holding point, probably because they reacted against the robotic assistance. Although MPCs look very promising for neurorehabilitation, further steps have to be taken to improve their technical limitations. Moreover, the effects of MPCs on motor learning should be evaluated

Dementia of Alzheimer Type can Alter both Languages in Late Bilinguals

Introduction Behavioral, clinical and neuroimaging evidence indicate that the first (L1) and the second language (L2) of bilingual individuals are supported by partly overlapping anatomo-functional pathways. While in the specific cases of patients suffering from cortical neurodegenerative diseases neuropsychological models predict that, in late bilinguals, L2 could be more impaired than L2, clinical data so far failed to demonstrate such dissociation. Method To address this question, we compared language performance in different tasks of oral and comprehension (semantic and syntactic) and production (naming, repetition, and fluency) in L1 and L2 in a group of 13 late proficient bilinguals with dementia of Alzheimer type (DAT) with 12 healthy late bilinguals matched in several demographic and linguistic factors including education level, age of L2 acquisition and immersion. Results Two-way mixed repeated-measure ANOVAs with factors Language and Group reveal main effects of Group (P<0.05) in all language tasks except for the counting and the sentence repetition tasks, indicating that DAT impact all aspects of language. Our analyses did not reveal any Group X Language interaction, suggesting that DAT impacted similarly on both languages. Conclusion Our results suggest that, like in stroke patients, neurodegenerative disease affects in a parallel manner oral language in L1 and L2, particularly at level of semantic, lexical and syntactic level of processing. These results do not support divergent models of bilingual brain representations, but rather argue for a substantially shared L1 and L2 network in late bilinguals

Reaching in Several Realities: Motor and Cognitive Benefits of Different Visualization Technologies

There is increasing interest in using virtual reality (VR) in robotic neurorehabilitation. However, the use of conventional VR displays (i.e., computer screens), implies several transformations between the real movements in 3D and their 2D virtual representations that might negatively impact the rehabilitation interventions. In this study, we compared the impact on movement quality and cognitive load of novel vs. standard visualization technologies: i) Immersive VR (IVR) head-mounted display (HMD), ii) Augmented reality (AR) HMD, and iii) Computer screen. Twenty healthy participants performed simultaneously a motor and a cognitive task. Goal-oriented reaching movements were recorded using an HTC Vive controller. The cognitive load was assessed by the accuracy on a simultaneous counting task. The movement quality improved when visualizing the movements in IVR, compared to the computer screen. These improvements were more evident for locations that required movements in several dimensions. We found a trend to higher movement quality in AR than Screen, but worse than IVR. No significant difference was observed between modalities for the cognitive load. These results provide encouraging evidence that VR interventions using HMDs might be more suited for reaching tasks in several dimensions than a computer screen. Technical limitations might still limit the beneficial effects of AR, both in movement quality and cognitive load