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When using a upper-limb prosthesis, mental, emotional, and physical effort is often experienced. These have been linked to high rates of device dissatisfaction and rejection. Therefore, understanding and quantifying the complex nature of workload experienced when using, or learning to use, a upper-limb prosthesis has practical and clinical importance for researchers and applied professionals. The aim of this paper was to design and validate a self-report measure of mental workload specific to prosthesis use (The Prosthesis Task Load Index; PROS-TLX) that encapsulates the array of mental, physical, and emotional demands often experienced by users of these devices. We first surveyed upper-limb prosthetic limb users who confirmed the importance of eight workload constructs taken from published literature and previous workload measures. These constructs were mental demands, physical demands, visual demands, conscious processing, frustration, situational stress, time pressure and device uncertainty. To validate the importance of these constructs during initial prosthesis learning, we then asked able-bodied participants to complete a coin-placement task using their anatomical hand and then using a myoelectric prosthesis simulator under low and high mental workload. As expected, using a prosthetic hand resulted in slower movements, more errors, and a greater tendency to visually fixate the hand (indexed using eye-tracking equipment). These changes in performance were accompanied by significant increases in PROS-TLX workload subscales. The scale was also found to have good convergent and divergent validity. Further work is required to validate whether the PROS-TLX can provide meaningful clinical insights to the workload experienced by clinical users of prosthetic devices.

Parkinson’s disease (PD) causes difficulties with hand movements, which few studies have 48 addressed therapeutically. Training with action observation (AO) and motor imagery (MI) improves performance in healthy individuals, particularly when the techniques are applied 50 simultaneously (AO+MI). Both AO and MI have shown promising effects in people with PD, but previous studies have only used these separately. Objective: This article describes the development and pilot testing of an intervention combining AO+MI and physical practice to improve functional manual actions in people with PD. Methods: The home-based intervention, delivered using a tablet computer app, was iteratively designed by an interdisciplinary team including people with PD, and further developed through focus groups and initial field testing. Preliminary data on feasibility was obtained via a six-week pilot randomised controlled trial (ISRCTN 11184024) of 10 participants with mild to moderate PD (6 intervention; 4 treatment as usual). Usage and adherence data were recorded during training, and semi-structured interviews were conducted with participants. Exploratory outcome measures including dexterity and timed action performance were tested. Results: Usage and qualitative data provided preliminary evidence of acceptability and usability. Exploratory outcomes also suggested that subjective and objective performance of manual actions should be tested in a larger trial. The importance of personalisation, choice, and motivation was highlighted, as well as the need to facilitate engagement in motor imagery. Conclusions: The results indicate that a larger RCT is warranted, and have broader relevance 69 for the feasibility and development of AO+MI interventions for people with PD and in other populations.

Parkinson’s disease (PD) causes difficulties with hand movements, which few studies have 48 addressed therapeutically. Training with action observation (AO) and motor imagery (MI) improves performance in healthy individuals, particularly when the techniques are applied 50 simultaneously (AO+MI). Both AO and MI have shown promising effects in people with PD, but previous studies have only used these separately. Objective: This article describes the development and pilot testing of an intervention combining AO+MI and physical practice to improve functional manual actions in people with PD. Methods: The home-based intervention, delivered using a tablet computer app, was iteratively designed by an interdisciplinary team including people with PD, and further developed through focus groups and initial field testing. Preliminary data on feasibility was obtained via a six-week pilot randomised controlled trial (ISRCTN 11184024) of 10 participants with mild to moderate PD (6 intervention; 4 treatment as usual). Usage and adherence data were recorded during training, and semi-structured interviews were conducted with participants. Exploratory outcome measures including dexterity and timed action performance were tested. Results: Usage and qualitative data provided preliminary evidence of acceptability and usability. Exploratory outcomes also suggested that subjective and objective performance of manual actions should be tested in a larger trial. The importance of personalisation, choice, and motivation was highlighted, as well as the need to facilitate engagement in motor imagery. Conclusions: The results indicate that a larger RCT is warranted, and have broader relevance 69 for the feasibility and development of AO+MI interventions for people with PD and in other populations.

Virtual Reality (VR) provides the potential for immersive and engaging training solutions for improving sport performance. However, if VR training is to be adopted and used in an effective and evidence-based fashion, a more rigorous assessment of the validity of the simulation is required. Construct validity is the degree to which the simulation provides an accurate representation of core features of the task. In the context of sport, if the training drills in the VR environment are a true representation of the skills needed in the real world, then those that excel at the sport in the real world should also excel in the virtual one. In this experiment, we examined the construct validity of a soccer-specific VR simulator by recruiting professional, academy, and novice players. Seventeen participants in each group completed four VR soccer drills and the VR software provided scores relating to performance and process (e.g., passing accuracy, composure, reaction time, and adaptability). Based on these scores, an algorithm gave a diagnostic score relating to the predicted ability of the player. Results showed that this VR platform successfully differentiated between participants of differing skill levels. These results provide some support for the construct validity of this VR simulator and suggest at least partial overlap between the perceptual-cognitive and motor skills needed to perform well across ‘real’ and virtual environments. Further work is needed to explore the validity and fidelity of the simulation before its adoption as a training device can be fully endorsed.

The dual-action simulation hypothesis proposes that both an observed and an imagined action can be represented simultaneously in the observer's brain. These two sensorimotor streams would either merge or compete depending on their relative suitability for action planning. To test this hypothesis, three forms of combined action observation and motor imagery (AO + MI) instructions were used in this repeated-measures experiment. Participants observed index finger abduction-adduction movements while imagining the same action (congruent AO + MI), little finger abduction-adduction (coordinative AO + MI), or a static hand (conflicting AO + MI). Single-pulse transcranial magnetic stimulation was applied to the left primary motor cortex. The amplitude of motor evoked potential responses were recorded from both the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the right-hand while eye movements were tracked. When controlling for the influence of relevant eye movements, corticospinal excitability was facilitated relative to control conditions in the concurrently observed and imagined muscles for both congruent and coordinative AO + MI conditions. Eye-movement metrics and social validation data from post–experiment interviews provided insight into the attentional and cognitive mechanisms underlying these effects. The findings provide empirical support for the dual-action simulation hypothesis, indicating for the first time that it is possible to co-represent observed and imagined actions simultaneously.

Research into attentional biases and threatening, pain-related information has primarily been investigated using reaction time as the dependent variable. This study aimed to extend previous research to provide a more in depth investigation of chronic back pain and individuals’ attention to emotional stimuli by recording eye movement behavior. Individuals with chronic back pain (n = 18) were recruited from a back rehabilitation program and age and sex matched against 17 non-symptomatic controls. Participants’ eye movements were recorded whilst they completed a dot probe task, which included back pain specific threatening images and neutral images. There were no significant differences between chronic pain and control participants in attentional biases recorded using reaction time from the dot probe task. Chronic pain participants, however, demonstrated a significantly higher percentage of fixations, larger pupil diameter, a longer average fixation duration and faster first fixation to threatening compared to neutral images. They also had a significantly longer average fixation duration and larger pupil diameter to threatening images compared to control participants. The findings of this study suggest eye gaze metrics may provide a more sensitive measure of attentional biases in chronic pain populations. These findings may have important therapeutic implications for the patient and therapist.