Exploring the impact of hand movement delays and hand appearance on myoelectric prosthesis embodiment using immersive virtual reality

Prosthesis embodiment, the feeling of a prosthesis being part of the user, is reported by some prosthesis users. Myoelectric prostheses are electrically powered which produce a delay with fixed and variable components. The latter introduces uncertainty over hand behaviour, likely influencing embodiment. Embodiment may also be influenced by hand appearance. An Immersive Virtual Reality experimental study is currently in preparation. It involves anatomically-intact participants to systematically measure the impact of movement delays and appearance on embodiment of a virtual prosthesis. This includes a head-mounted display and motion tracking of a myoelectric prosthesis, with various virtual appearances and hand-movement delays

“Thanks for letting us all share your mammogram experience virtually” : developing an online hub for cancer screening

Background: The decision around whether to attend breast screening can often involve making sense of confusing and contradictory information on risks and benefits. The Word of Mouth Mammogram e-Network (WoMMeN) project was established to create an online resource to support decision making around breast screening. This paper presents data from our user-centred approach to engaging stakeholders (both health professionals and service-users) in the design of this online resource. Our novel approach involved creating a user-design group within Facebook to allow access to ongoing discussion between researchers, radiographers and existing and potential service-users. Objective: The current study had two objectives. The first was to examine the utility of an online user-design group for generating insight for the creation of online health resources. We sought to explore the advantages and limitations of this approach. The second objective was to analyse what women want from an online resource for breast screening information. Methods: We recruited a user-design group in Facebook, and also posted a survey within the group asking questions around design considerations for an online breast screening hub. Although the membership of the Facebook group varied over time, there were 71 members in the Facebook group at the end point of analysis. We next conducted framework analysis on 70 threads from Facebook and thematic analysis on the 23 survey responses. We focused additional analysis on how the themes were discussed by the different stakeholders within the context of the design group. Results: Two major themes were found across both the Facebook discussion and the survey data: ‘The power of information’, and ‘The hub as a place for communication and support’. Information was discussed as empowering, but also recognised as threatening. Communication and the sharing of experiences were deemed important but there was also recognition of potential miscommunication within online discussion. Health professionals and service-users expressed the same broad concerns, but also showed subtle differences. Importantly, the themes were triangulated between the Facebook discussions and the survey data, supporting the validity of an online user-design group. Conclusions: Online user-design groups afford a useful method for understanding stakeholder needs. In contrast to focus groups, they afford access to users from diverse geographical locations, and traverse time constraints allowing more considered follow-ups to responses. The use of Facebook provides a familiar and naturalistic setting for discussion. Whilst also acknowledging limitations in the sample, this approach has allowed us to understand the views of stakeholders in the user-centred design of the WoMMeN hub for breast screening

Charities’ use of Twitter : exploring social support for women living with and beyond breast cancer

Twitter is one social media platform that enables those experiencing breast cancer to access support from others. This study explores how cancer charities provide support to women living with and beyond breast cancer (LWBBC) through their Twitter feeds. Seven hundred and seventy-two tweets from seven purposively sampled cancer charities were used to explore Twitter posts made relating to social support. Two questions were posed: (1) what type of support is positioned by cancer charities on Twitter for women LWBBC and (2) what themes emerge from tweet content pertaining to support for women LWBBC? Using a peer-reviewed typology of ‘social support’ [Rui, J., Chen, Y., & Damiano, A. (2013). Health organizations providing and seeking social support: A twitter-based content analysis. Cyberpsychology, Behavior, And Social Networking, 16(9), 669–673. doi:10.1089/cyber.2012.0350], a deductive content analysis was utilised to identify informational, instrumental or emotional social support tweets (n = 199). Over half (56%) of tweets offered informational support; 27% provided or sought instrumental support and 18% related to emotional support. Interestingly, 74.3% (n = 573) of tweets were not related to providing or seeking social support. An inductive qualitative thematic analysis of the 199 tweets identified the focus (i.e., themes) of support. Three themes were identified: (1) raising awareness, (2) focusing on the future and (3) sharing stories. Cancer charities predominantly use Twitter to signpost women to informational resources and to seek instrumental support to meet charitable objectives. As the number of women LWBBC continues to increase, this study provides valuable insight into how charities represent themselves on Twitter in relation to the social support needs of women LWBBC

Psychophysiological indices of cognitive style : a triangulated study incorporating neuroimaging, eye-tracking, psychometric and behavioral measures

Employing a triangulated design to explore psychophysiological indices of cognitive style, the study investigated the validity of the intuition-analysis dimension of cognitive style and its associated construct measure, the Cognitive Style Index (CSI). Participants completed a comparative visual search (CVS) task whilst changes in hemodynamic concentrations in the prefrontal cortex (PFC) were monitored using functional near-infrared spectroscopy and eye movements were recorded together with task performance measures of response time and accuracy. Results revealed significant style-related differences in response time and number of saccades. Analysts were characterized by fewer saccadic eye movements and quicker response times - but with comparable accuracy scores - compared to intuitives, suggesting a more efficient visual search strategy and decision-making style on the experimental task. No style-related differences in neural activation were found, suggesting that differences were not mediated by style-specific variations in brain activation or hemispheric lateralization. Task-evoked neural activation - compared with baseline resting state - represented the value of PFC-based neural activation measures in studies of cognitive processing. Findings demonstrated style-related differences supporting the intuition-analysis dimension of cognitive style and the validity of the CSI as a psychometric measure of style. The potential value of valid psychometric measures of cognitive style in applied areas is highlighted. Key words: cognitive style, information processing, Cognitive Style Index, functional near-infrared 21 spectroscopy, eye-tracking, neuroimaging, Bayesian statistic

The reality of myoelectric prostheses : understanding what makes these devices difficult for some users to control

Users of myoelectric prostheses can often find them difficult to control. This can lead to passive-use of the device or total rejection, which can have detrimental effects on the contralateral limb due to overuse. Current clinically available prostheses are ‘open loop’ systems, and although considerable effort has been focused on developing biofeedback to “close the loop”, there is evidence from laboratory-based studies that other factors, notably improving predictability of response, may be as, if not more, important. Interestingly, despite a large volume of research aimed at improving myoelectric prostheses, it is not currently known which aspect of clinically available systems has the greatest impact on overall functionality and everyday usage. A protocol has therefore been designed to assess EMG skill of the user and predictability of the prosthesis response as significant parts of the control chain, and to relate these to functionality and everyday usage. Here we present the protocol and results from early pilot work. A set of experiments has been developed. Firstly to characterize user skill in generating the required level of EMG signal, as well as the speed with which users are able to make the decision to activate the appropriate muscles. Secondly, to measure unpredictability introduced at the skin-electrode interface, in order to understand the effects of the socket mounted electrode fit under different loads on the variability of time taken for the prosthetic hand to respond. To evaluate prosthesis user functionality, four different outcome measures are assessed. Using a simple upper limb functional task prosthesis users are assessed for (1) success of task completion, (2)task duration, (3) quality of movement, and (4) gaze behavior. To evaluate everyday usage away from the clinic, the symmetricity of their real-world arm use is assessed using activity monitoring. These methods will later be used to assess a prosthesis user cohort, to establish the relative contribution of each control factor to the individual measures of functionality and everyday usage (using multiple regression models). The results will support future researchers, designers and clinicians in concentrating their efforts on the area which will have the greatest impact on improving prosthesis use

Upper limb activity of twenty myoelectric prosthesis users and twenty healthy anatomically intact adults

The upper limb activity of twenty unilateral upper limb myoelectric prosthesis users and twenty anatomically intact adults were recorded over a 7-day period using two wrist worn accelerometers (Actigraph, LLC). This dataset reflects the real-world activities of the participants during their normal day-to-day routines. Participants included students, working adults, and retirees recruited from across the United Kingdom. This is the first published dataset of its kind and offers a potential wealth of knowledge into a poorly understood cohort. The raw unprocessed data files and the activity count data exported from the Actilife software are provided. We also provide a non-wear algorithm developed for the removal of prosthesis non-wear periods and resulting activity count data corresponding to prothesis wear periods. Finally, we have included the transposed activity diaries provided by the participants. Analysis to date has primarily involved assessment of the symmetry of upper limb activity, however, there is potential to undertake additional analysis such as understanding the differences in the way a prosthesis is used compared to an anatomical arm

Why does my prosthetic hand not always do what it is told?

There are online videos that appear to show electrically powered prosthetic (artificial) hands to be near-perfect replacements for a missing hand. However, for many users, the reality can be quite different. Prosthetic hands do not always respond as expected, which can be frustrating. A prosthetic hand is controlled by muscle signals in the remaining part of the person’s affected arm, using sensors called electrodes. The electrodes are embedded within the socket, which is the part of the prosthetic arm that connects it to the person’s arm. When they activate their muscles, the hand can open, close, or change its grip. If the socket moves, it can pull the electrodes away from the skin. As a result, the muscle activity signaling the person’s intention cannot be properly detected, and the hand will not work very well. In this article, we explain why socket fit may be the most important part of a prosthetic arm

Addressing unpredictability may be the key to improving performance with current clinically prescribed myoelectric prostheses

The efferent control chain for an upper-limb myoelectric prosthesis can be separated into 3 key areas: signal generation, signal acquisition, and device response. Data were collected from twenty trans-radial myoelectric prosthesis users using their own clinically prescribed devices, to establish the relative impact of these potential control factors on user performance (user functionality and everyday prosthesis usage). By identifying the key factor(s), we can guide future developments to ensure clinical impact. Skill in generating muscle signals was assessed via reaction times and signal tracking. To assess the predictability of signal acquisition, we inspected reaction time spread and undesired hand activations. As a measure of device response, we recorded the electromechanical delay between electrode stimulation and the onset of hand movement. Results suggest abstract measures of skill in controlling muscle signals are poorly correlated with performance. Undesired activations of the hand or incorrect responses were correlated with almost all kinematics and gaze measures suggesting unpredictability is a key factor. Significant correlations were also found between several measures of performance and the electromechanical delay; however, unexpectedly, longer electromechanical delays correlated with better performance. Future research should focus on exploring causes of unpredictability, their relative impacts on performance and interventions to address this

Upper- and lower-limb amputees show reduced levels of eeriness for images of prosthetic hands

The uncanny phenomenon describes the feeling of unease associated with seeing an image which is close to appearing human. Prosthetic hands in particular are well-known to induce this effect. Little is known, however, about this phenomenon from the viewpoint of prosthesis users. We studied perceptions of eeriness and human-likeness for images of different types of mechanical, cosmetic, and anatomical hands in upper-limb prosthesis users (n=9), lower-limb prosthesis users (n=10), prosthetists (n=16), control participants with no prosthetic training (n=20), and control participants who were trained to use a myoelectric prosthetic hand simulator (n=23). Both the upper- and lowerlimb prosthesis user groups showed a reduced uncanny phenomenon (i.e., significantly lower levels of eeriness) for cosmetic prosthetic hands compared to the other groups, with no concomitant reduction in how these stimuli were rated in terms of human-likeness. However, a similar effect was found neither for prosthetists with prolonged visual experience of prosthetic hands, nor for the group with short-term training with the simulator. These findings in the prosthesis users therefore seem likely to be related to limb absence or prolonged experience with prostheses