Brain-Computer interfaces for communication: preferences of individuals with locked-in syndrome, caregivers and researchers

Abstract

Objectives: The development of Brain-Computer Interfaces to restore communication (cBCIs) in people with severe motor impairment ideally relies on a close collaboration between end-users and other stakeholders, such as caregivers and researchers. Awareness about potential differences in opinion between these groups is crucial for development of usable cBCIs and access technology (AT) in general. In this study, we compared the opinions of prospective cBCI users, their caregivers and cBCI researchers regarding: (1) what applications would users like to control with a cBCI; (2) what mental strategies would users prefer to use for cBCI control; and (3) at what stage of their clinical trajectory would users like to be informed about AT and cBCIs.

Methods: We collected data from 28 individuals with locked-in syndrome, 29 of their caregivers and 28 cBCI researchers. The questionnaire was supported with animation videos to explain different cBCI concepts, the utility of which was also assessed.

Results: Opinions of the three groups were aligned with respect to the most desired cBCI applications, but diverged regarding mental strategies and the timing of being informed about cBCIs. Animation videos were regarded as clear and useful tools to explain cBCIs and mental strategies to end-users and other stakeholders.

Conclusions: Disagreements were clear between stakeholders regarding which mental strategies users prefer to use and when they would like to be informed about cBCIs. To move forward in the development and clinical implementation of cBCIs, it will be necessary to align the research agendas with the needs of the end-users and caregivers.IMPLICATIONS FOR REHABILITATIONBrain-Computer Interfaces may offer people with severe motor impairment a brain-based and muscle-independent approach to control communication-technology. The successful development of communication BCIs (cBCIs) relies on a close collaboration between end-users and other stakeholders, such as caregivers and researchers.Our work reveals that people with locked-in syndrome (end-users), their caregivers and researchers developing cBCIs agree that direct and private forms of communication are the most desired cBCI applications, but disagree regarding the preferred mental strategies for cBCI control and when to be informed about cBCIs.Animation videos are an effective tool for providing information to individuals, independent of their level of health literacy, regarding the concept of cBCIs and mental strategies for control.The misalignment in opinions of different groups of stakeholders about cBCIs strengthens the argument for a user-centered design approach in the development of cBCIs and access technology designed for daily life usage.

Keywords: Brain-computer interface; caregivers; communication; locked-in syndrome; researchers; user-centred design.

Figure 1 –. Representative screenshots of the animation videos used in the questionnaire.

Three illustrative screenshots of the videos used to explain the concept of BCIs, BCI-based communication and mental strategies that can be used to control the BCI. For simplicity and consistency across mental strategies, we used a spelling matrix as a control application (middle panel) and a button press (and subsequent letter selection) as a control output (upper panel).

Figure 2 –. Demographic description of the users, caregivers and researchers.

Demographic information of the users (N=28), caregivers (N=29) and researchers (N=29) included in this study was extracted from Section 1 of the questionnaire. A) Information (in percentage) about the user’s gender (male, female), age group (≤ 50 years old, > 50 years old), living situation (at home or at a nursing home), etiology (neuromuscular disease, NMD; sudden onset, SO) and whether they were naïve to BCI. B) Information (in percentage) about the caregiver’s gender (male, female), age group (≤ 50 years old, > 50 years old), personal/professional relation to the user (family member, professional caregiver), type of LIS of individual the caregiver takes care of (neuromuscular disease, NMD; sudden onset, SO), and whether they were naïve to BCI. C) Information (in percentage) about the researcher’s gender (male, female), age group (≤ 50 years old, > 50 years old), continent of residence (Asia, Europe or North America), and whether they worked with individuals with locked-in syndrome (LIS) and communication Brain-Computer Interfaces (cBCIs). Bar plots indicate most used signal acquisition techniques by researchers in their line of work, as well as the most investigated mental strategies for controlling a BCI.

Figure 3 –. Comparison between users’ current AT application and expected cBCI applications.

A) Ranking of preferred applications to be supported by a cBCI, using the center-of-mass (COM) metric. Meaningful differences between groups were estimated using the Monte Carlo variance indicated on the top right corner (0.32). In addition, the size of the Monte Carlo variance is indicated on top of the one bar that showed a larger-than-Monte-Carlo-variance difference from users. Rating scales ranged from 1 (least preferred) to 6 (most preferred). B) Percent of users that have a specific AT application currently available at home (dark green, highlighted with black line) compared with the importance of these applications as rated by the caregivers (green) and researchers (light green). C) Median and median absolute deviation (error bars) of how often each application was (estimated to be) used. Of note, the frequency of usage of each application was computed from the number of participants that selected that specific application in B (gray bars; units in the right-side y-axis; copies of the information given in B).

Figure 4 –. Comparison between users’, caregivers’ and researchers’ opinion about mental strategies.

A) Center-of-mass (COM) values computed for the top 4 mental strategies for users, caregivers and researchers. Note that caregivers rank their preference from their own perspective (as an abled control group), whereas researchers ranked from the perspective of the users. Monte Carlo variance is indicated on the top right corner of each panel and at each caregiver/research bar of which the difference with the user bar is larger or smaller than the Monte Carlo variance (0.28). Ranking scales ranged from 1 (least preferred) to 4 (most preferred). B-C) Percent of participants that rated each strategy (in a 5-points Likert scale) according to how easy (B) and how enjoyable (C) it is. The charts position the % of replies vertically such that positive responses are stacked above the horizontal baseline (0%) and negative responses are stacked below the baseline. The ‘neutral’ is centered around 0%. Mental strategies highlighted in gray showed a statistically significant difference between groups (Kruskal Wallis test, p < 0.05, Bonferroni corrected for 8 repetitions). For the strategies with significant difference between groups, pair-wise Mann-Whitney tests were used to test which groups were statistically different between users and researchers or caregivers (* < 0.05).

Figure 5 –. Results of time of AT information ratings.

Opinion of participants (in percentage) per group (users, caregivers and researchers) about the timing of information delivery on AT and cBCIs for people with LIS due to neuromuscular disorder (A: NMD) or sudden onset (B: SO).

Figure 6 –. Animation videos feedback from users, caregivers and researchers.

A) The three respondent groups (users, caregiver and researchers) rated the animation videos introducing each mental strategy according to how clear it was, using a 5-points Likert scale. Videos on mental strategies highlighted in gray showed a statistically significant difference between groups (Kruskal Wallis test, p<0.05, Bonferroni corrected for 8 repetitions). For the strategies with a significant difference between groups, pair-wise Mann-Whitney tests were used to test which groups (caregivers/researchers) were statistically different from the users (* < 0.05). B) Percent of researchers that reported that the animation videos were a clear (or not) means to introduce cBCIs and mental strategies to user and other stakeholders (Yes = clear; No = not clear).