Topical Review Article
Trends in Communicative Access Solutions for Children With Cerebral Palsy
Journal of Child Neurology 2014, Vol. 29(8) 1108-1118 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0883073814534320 jcn.sagepub.com
Andrew Myrden, MASc1,2, Larissa Schudlo, MASc1,2, Sabine Weyand, MASc1,2, Timothy Zeyl, MASc1,2, and Tom Chau, PhD, PEng1,2
Abstract Access solutions may facilitate communication in children with limited functional speech and motor control. This study reviews current trends in access solution development for children with cerebral palsy, with particular emphasis on the access technology that harnesses a control signal from the user (eg, movement or physiological change) and the output device (eg, augmentative and alternative communication system) whose behavior is modulated by the user’s control signal. Access technologies have advanced from simple mechanical switches to machine vision (eg, eye-gaze trackers), inertial sensing, and emerging physiological interfaces that require minimal physical effort. Similarly, output devices have evolved from bulky, dedicated hardware with limited configurability, to platform-agnostic, highly personalized mobile applications. Emerging case studies encourage the consideration of access technology for all nonverbal children with cerebral palsy with at least nascent contingency awareness. However, establishing robust evidence of the effectiveness of the aforementioned advances will require more expansive studies. Keywords cerebral palsy, children, communication, access technology Received April 02, 2014. Received revised April 02, 2014. Accepted for publication April 03, 2014.
It is estimated that 40% of children with cerebral palsy, particularly those at Gross Motor Function Classification System level IV or V, experience some degree of difficulty with expressive communication.1 Communication restrictions have been associated with delayed language development2 and reduction in peer interactions, self-esteem, and quality of life.1,3 Consequently, children, parents, and health care providers have identified communication enhancement as a high-priority therapy goal in cerebral palsy.1,3,4 Indeed, functional communication fosters independence, reveals a child’s true developmental status, and allows a child to be involved in his or her care.5 Children with cerebral palsy who have complex communication needs can benefit from access solutions that provide alternative means of communication. As shown in Figure 1, a communication access solution has 3 components—the access pathway, a signal processing unit, and the augmentative and alternative communication system.3,6 The access pathway refers to the input used to control the system, which traditionally might be direct (eg, touching the augmentative and alternative communication device’s screen to select the object of interest) or indirect (eg, waiting for an on-screen keyboard to scan to the desired letter and then contacting one or more mechanical switches external to the augmentative and alternative communication
device to make a selection). The former is user-paced whereas the latter is system-paced. The signal processing unit embodies an algorithm that processes the user input. Collectively, the access pathway and signal processing unit constitute the access technology.6 The augmentative and alternative communication system refers to the user interface, which can be grouped into one of 3 categories: low, mid, and high-tech. Low-tech augmentative and alternative communication systems include nonelectronic devices such as printed communication boards. Mid-tech augmentative and alternative communication systems include electronic devices with a single static display and/or a scanning system with one level of choice. Finally, high-tech
1
Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Road, Toronto, Ontario, Canada 2 Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, Canada Corresponding Author: Tom Chau, PhD, PEng, Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Road, Toronto, Ontario M4G 1R8, Canada. Email: [email protected]
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Figure 1. Schematic of a communication access solution. The access technology consists of an access pathway and signal processing unit.
augmentative and alternative communication systems have dynamic displays and/or several layers of choices.3 Early introduction of access solutions for children with cerebral palsy can enable communication and promote the development of spoken language.7 Sevcik and colleagues8(p1328) proposed that access solutions should be a ‘‘first line of intervention’’ that can ‘‘set the stage for further language and communication development’’ for young children with communication difficulties. Nonverbal children with cerebral palsy can interact with their communication partners by using gestures or vocalizations. These forms of communication require some degree of motor control on the part of the child. On the other hand, interpretation of such communicative attempts requires that the communication partner possess a high degree of familiarity with the child, including his or her behavioral idiosyncrasies, movement patterns,9 personal preferences,10 and daily routine. Successful communication also necessitates close attention to subtle physical cues, such as changes in the child’s body posture, eye gaze, facial expressions, vocalizations, and muscle tone. Clearly, such stringent prerequisites limit the potential number of functional communication partners for the child, as each partner must be intimately attuned to the child’s temperament and all the aforementioned behaviors. Access technologies remove some of this dependence on communication partners, allowing children to independently control augmentative and alternative communication devices and thereby develop communication abilities in a variety of social environments.10,11 This article presents a scoping review of the current trends in access solutions for children with cerebral palsy, based on both scientific and gray literature, and the implications for clinical practice. We present the search methods, search results arranged by access technology and augmentative and alternative communication device, and a brief discussion, including emergent research.
Methods Using the keywords cerebral palsy, communication, technology, and children (synonyms and variations thereof), we searched the following databases: Web of Science, Google Scholar, Scopus, ProQuest, and Compendex databases, for journal articles published between 2008 and October 2013. The search yielded 61 candidate articles. This list was further filtered down to 20 articles that deployed a technologybased communication solution, relating to the production of speech or text, for at least 1 young person (18 years of age or younger) with cerebral palsy. In addition, we also combed the gray literature by initially searching ProQuest with the terms communication, technology, and augmentative and alternative communication in all search fields. All information sources (blogs, podcasts, trade journals, magazines, conference proceedings, etc) except dissertations and theses were included. The search yielded 3921 items, which were then screened for relevancy to the topic area (ie, augmentative and alternative communication technology for children with cerebral palsy), yielding 37 different access solutions. For those that involved products and apps that had been released since 2008, we further visited the manufacturer or vendor websites as available to collect additional information.
Results Our scan of the scientific and gray literature identified a changing landscape in terms of both access technologies and augmentative and alternative communication devices. The key findings will be presented under these 2 main categories below.
Access Technologies Over the past several decades, the proliferation of consumer electronics has enabled many new means of communication for children with cerebral palsy who are nonverbal, which roughly constitutes a quarter of the pediatric cerebral palsy population.12 For those with some controlled movement, standard (eg, trackballs, joysticks, mice, and keyboards) or adapted (eg, mechanical switches) input devices can facilitate access
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Table 1. High-Tech Augmentative and Alternative Communication Devices Currently on the Market (Released Since 2008). Device
Description
Release date
Tobii® I-SeriesI12,13 I1513 AccentÔ 1000,14 120015 ComLinkProSlate 4Ô,16 8Ô,17 10Ô18
Symbol-grid system and text-to-speech Symbol-grid system Load with choice of iOS app such as Proloquo2go, SonoFlex and others. Symbol-grid system and text-to-speech
May 2013 November 2012 4, 8: July 2011, 10: November 2012
Symbol-grid system Wearable augmentative and alternative communication system—converts ComLinkdevice or iPod/iPad to wearable augmentative and alternative communication device with speaker Symbol-grid system Symbol-grid system and text-to-speech Symbol-grid system and text-to-speech Symbol-grid system and text-to-speech Symbol-list system and text-to-speech Text-to-speech Text-to-speech Text-to-speech Tablet with built-in eye gaze
January 2012 July 2011
ComLinkLT(3G)Ô,19 ComLinkLT(3G)Ô with Enable Eyes20 ECO221 SoundPODÔ22
PowerBox 723 Tobii® C-Series C8,24 C12,25 C1526 DynaVox MaestroÔ27 DynaVox Xpress Ô 2.028 Tango!29 Lightwriter® SL4030 DynaWriteÔ 2.031 Tellus 432 Sahara EyeSlate33
January 2012
June 2011 8, 12: January 2009, 15: January 2011 October 2010 August 2010 February 2009 June 2013 June 2011 2010 June 2013
Table 2. Commercially Available Augmentative and Alternative Communication Apps Released Since 2008. App
Description
Compatible platforms
TalkingTILES34
Symbol-grid system Access method: touch Symbol-grid system and text-to-speech Access methods: touch, adaptive switch, adjustable direct touch Symbol-list system, photo story Access methods: touch, keyboard, Bluetooth switch Symbol-grid system Access methods: touch, Bluetooth switch Symbol-grid system and text-to-speech Access methods: touch Symbol-grid system, photo story Access methods: touch, another iPad/ iPod with Attainment Switch39 app, Bluetooth switch Photo story, add videos and audio to personal photos Access methods: Bluetooth switch, Therapy Box Switch Box, ‘‘touch anywhere’’ scanning Symbol-grid system. Simple vocabulary, not customizable Access method: touch Symbol-grid system Access method: touch, Bluetooth switch Text-to-speech Accommodates shaky or inexact key selections. Access method: touch Text-to-speech Access method: touch
iOS and Android
$299.99
iOS
$219.99
Proloquo2go®35 TalkRocketGo36 MyTalkTools Mobile37 Sono Flex11 GoTalk NOW38 Scene&Heard40 Speech Button41 SoundingBoardÔ42 RocketKeys43 Verbally44
to communication via specialized augmentative and alternative communication hardware (Table 1) or augmentative and alternative communication software applications (Table 2) on generic computing platforms. For those capable of deictic gestures (eg, pointing), capacitive and resistive touch screen technologies
Cost (USD)
iOS and Android
$99.99
iOS
$99.99
iOS, Android, PCs, Kindle Fire, devices with Tobii Communicator iOS (iPad only)
$99.99 $79.99
iOS
$49.99
iOS
$7.99
iOS
Free
iOS and Android
iOS (iPad only)
$159.99
Free
offer direct access to communication devices and applications (eg, Noren et al9). Likewise, individuals who can control intraoral air pressure (eg, via buccinator muscles and diaphragm) may be able to operate a ‘‘sip and puff’’ switch. These motor-based access methods can be effective when
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Table 3. Recent Studies Investigating Access Technologies for Children With Cerebral Palsy.
Category
Physiological input
Access pathway
Functional activity
No. of children with cerebral palsy Authors
Skin temperature, heart Autonomic rate, respiration nervous system signals
Temperature, blood volume pulse, Communicate emotional state and electrodermal activity sensors and respiration belt
1
Memarian51
Hand/foot
Video camera, image processing
4
Gonzalez52
Movement of hand and foot, Hand movements,
Control cursor
Eyes
Select letter from on-screen keyboard Hyperkinetic movement Accelerometer on upper limbs, head Communicate preference Facial expression, Video camera, image processing Communicate emotional state Tongue protrusion, Video camera Select graphical icon Mouth opening Thermal camera Select letter from on-screen keyboard Eye Gaze Eye tracker Select graphical icon
Head
Head movement,
Vocalization
Head movement, Head movement Humming
Mouth/Face
Pressure sensing microswitch
Accelerometer, gyroscope, magnetometer Video camera, image processing Gyroscope Accelerometer on throat
they cater to the specific capabilities of an individual with cerebral palsy.45-49 However, for many children with cerebral palsy, these access technologies are not plausible because of difficulties with switch targeting, mounting and positioning, activation with kinetic sufficiency, and release following activation.50
Inertial, Computer Vision, and Physiological Access Pathways With the emergence of light weight, cost-effective sensors, advances in mobile computing hardware and new developments in pattern recognition software, individualized access technologies incorporating custom-placed sensors and personalized signal processing have become increasingly prominent in scientific literature. Table 3 provides an overview of some recent literature on state-of-the art access technologies that have been tested with modest samples of children with cerebral palsy. These technologies include video and thermal cameras that can detect and interpret limb movements, head motion and facial expressions; pressure sensors that detect switch depression with individual-specific sensitivity; magnetometers, gyroscopes, and accelerometers that sense position, angular velocity, and vibration for the purpose of detecting limb movement and vocalizations; and eye-gaze trackers that enable cursor control and icon selection. Some of these technologies are now commercially available. For example, many augmentative and alternative communication companies now offer eye gaze as an alternative access method, with the possibility of interfacing to a tablet computer.33,51
Control cursor Control cursor Control cursor Select letter from on-screen keyboard
1 10
Lancioni53,54 Stasolla55 Lesperance56 Ann44,57
1 1
Leung12 Memarian58
5
Amantis59
2,3
Raya60,61
1,1,3
4 2 2
Gonzalez52 Mukherjee62 Falk63
Enabling Passive Communication In addition to active communication, where the user explicitly attempts to express himself or herself, access technologies are also being developed for passive communication. For the subset of nonverbal children who may not be able to initiate communication or respond to questions using an access pathway (ie, typically those for whom contingency awareness remains ambiguous), it is believed that enabling passive communication, that is, the automatic decoding of affective state, response to environmental stimuli, and/or personal preference may enhance their quality of care and ultimately quality of life.52 Such information could inform the interaction with these children, including the choice of therapeutic activities, toys, and food. For this goal, researchers have investigated the usage of video cameras and various physiological sensors to track changes in skin temperature, heart activity, electrodermal activity, respiration, and facial expressions in response to certain stimuli and environmental contexts.53-55 Accelerometry has also been exploited for the automatic decoding of preferences of nonverbal children with hyperkinetic movements.56 Although the above-cited studies present some promising early case evidence, the general effectiveness of these passive access modalities remains to be proven. A fundamental challenge in establishing effectiveness is the absence of ground truth; that is, these children and youth cannot confirm the verity of the inferred state or response, and often a subjective proxy validation (eg, parent or familiar caregiver) is all that is available. The fallibility of such proxy validations is highlighted by a recent study that unveiled potential inconsistencies between parental interpretation of the behavioral manifestations of preference
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of a nonverbal, contingently unaware adolescent with cerebral palsy, and quantitative measures of his autonomic responses.57
Outstanding Challenges Although the number of available access technologies has increased, evidence of their clinical effectiveness is, for the most part, only emerging. Most studies in the scientific literature have either been case studies or have, often for pragmatic reasons, tested a very small sample of pediatric participants with cerebral palsy. Nonetheless, studies to date have shown, on a small sample basis, that advanced access technologies have the ability to reduce physical exertion, increase communication efficiency, and increase accuracy over that achievable with existing input methods (eg, Falk44). However, recently proposed access technologies are not immune to accidental activation by involuntary movements (eg, primitive reflexes) or voluntary movements that are not intended to control the access solution.45 A classic depiction of this dilemma is the so-called Midas Touch predicament, in which a targeted access site bears both a technology-control intention (eg, eye gaze to move cursor) and a no-tech expressive communication function (eg, vertical eye movements to express yes or no to a communication partner). These false activations are of particular concern because of their tendency to cause unpredictable behavior in the access solution, potentially leading to frustration, learned helplessness, and abandonment.58 It is difficult to compare accuracies of various access technologies across case studies, as they are largely dependent on the abilities of the participant, the appropriateness of the prescribed access technology for the individual, and the magnitude and quality of training provided to the user and his or her communication partners.11
Augmentative and Alternative Communication Devices Recent Developments in Mid-Tech Communication Solutions Traditionally, the most common electronic augmentative and alternative communication devices were mid-tech, an umbrella term encompassing static, single, and multimessage speechgenerating devices that produce a fixed number of messages. The simplest are those that play recorded voice messages with the push of a button. Although these devices were typically single- or dual-message communicators, like the iTalk2Ô,59 BIG/ LITTLEmackÔ,60,61 and TalkingBrixÔ,62 there are now variants that offer an unlimited number of output messages that play in sequence, such as BIG/LITTLE Step-by-StepÔ,63 or even multiple sequences, as in the BIG/LITTLE Step-by-Step with Levels.64 For multimessage output, static electronic communication boards offer greater flexibility. Many boards, such as the Tobii® S32,65 GoTalk Series,66 SuperTalkerÔ Progressive Communicator,67 and the QuickTalkerÔ Family of Communication Devices,68 contain multiple locations that play voice
messages when selected. Some devices, such as the Tobii S32 Scan, GoTalk, and SuperTalker, also use custom-made interchangeable overlays that allow different recorded messages to play with each overlay. Other boards, such as the QuickTalker series, include multiple levels, with each level producing a new set of output messages. Although this eliminates the need for multiple overlays, the number of messages is limited, and the images associated with each frame do not change with the audio. Additionally, these boards all support touch input, but do not always accommodate switch inputs. These mid-tech augmentative and alternative communication devices are readily available. They are easy to use and learn, making them particularly suitable for young children.69 Although they can be portable and lightweight, they are generally bulkier and less versatile than high-tech alternatives.
Migration to Mobile Platforms: High-Tech Communication Solutions High-tech options have become prevalent over the past 20 years,70 as technological advances have allowed the design of dynamic augmentative and alternative communication devices. Rather than producing a single output for each input, these devices are coded, permitting multiple possible outputs for a limited number of inputs.71 In comparison to static boards, dynamic screen communication devices provide a larger vocabulary to the user at one time, enabling more natural and responsive communication. Until recently, the market for high-tech, dynamic augmentative and alternative communication devices was dominated by a small number of companies.72 These companies produced a limited number of dedicated systems, or systems that could only be used for communication.73 However, because of the mobile technology revolution, the use of mobile smart phones and tablets for augmentative and alternative communication has become widespread.74-76 This adaptation of mainstream hardware has created a significant paradigm shift in high-tech augmentative and alternative communication devices, as these popular communication tools offer several advantages over traditional systems, including cost,75-78 ease of use,74,75,77 availability,79 transportability,75,76,80 and social acceptance.69,74,75,81 Additionally, these multifunctional mobile devices provide access to mainstream phone applications, such as text messaging, e-mail, and internet browsing, which have become essential aspects of communication.76,82,83 Table 1 presents a list of high-tech augmentative and alternative communication systems that are commercially available at the time of writing.
Growing Abundance of Apps Because of the economic and social appeal of deploying mainstream consumer technology for communication, there has been a recent surge in the number of mobile augmentative and alternative communication applications, or ‘‘apps.’’74,75 Assistive communication apps are currently available for a variety of platforms including Android, Windows, and most popularly,
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iOS (Apple Inc’s mobile operating system for iPods, iPhones, and iPads).78 Although augmentative and alternative communication users are now afforded a diversity of cost-effective, easily attainable options, most apps have been developed by programmers who do not necessarily possess knowledge in language development.74,82 Consequently, not all apps represent language concepts in a manner that is conducive to learning and optimizing communication. Unlike devices purchased from large augmentative and alternative communication companies,79 these apps can be easily purchased without the input of a clinician. Thus, failure to reap the anticipated benefits of augmentative and alternative communication may simply be due to a mismatch between the specific app’s functions and the individual user’s needs. Furthermore, many apps do not support connections to alternative access technologies. Unfortunately, minimal research has focused on improving the design of augmentative and alternative communication apps, even though simple design changes can often substantially impact communication performance.83 Many app purchases are currently driven by hype, rather than an understanding of what is required to optimize communication for a specific user, information typically derived from a systematic, multidisciplinary assessment of the user’s needs and abilities.76 Table 2 presents an abbreviated list of some popular augmentative and alternative communication apps.
Enhanced Personalization Many augmentative and alternative communication devices and apps are now highly customizable. Features that can be personalized include vocabulary content and organization, visual appearance, and audio output. This flexibility allows the communication aid to be tailored to a specific user. However, device customization can be very time-consuming,77 especially for apps that require the creation of all graphics and communication pages from scratch.84-86 Nonetheless, apps are typically more intuitive to program than dedicated communication systems.77 Additionally, there is growing multilingual support within augmentative and alternative communication apps. At the time of this writing, some apps (eg, TalkingTILES87) already provide more than 40 different language alternatives and accommodate non-English symbols. Indeed, the incorporation of language-specific grammar has been identified as a general principle for ensuring clarity of meaning in non-English augmentative and alternative communication systems.88 Most augmentative and alternative communication systems employ symbol-based communication, in which symbols (that produce spoken words or phrases when selected) are organized into grids or lists. To continuously customize the user’s vocabulary, typically, new words or phrases can be added, as needed, and grouped topically, to form communication pages.13-20,84-87,89 Pages can also link to other groups of symbols or pages to provide more extensive organization. This allows caregivers, teachers, and clinicians to personalize the system and quickly respond to changing communication needs. However, complex organizations that require navigation through multiple
screens to locate the desired symbol can be overwhelming for the user,69,83 especially for young children or individuals with cognitive impairments. Augmentative and alternative communication layouts that use simple, sequential navigation though communication pages may be more appropriate for these individuals.21,86 The focus should be on strengthening communication and language concepts rather than simply exploiting technological advancements to enhance the complexity of augmentative and alternative communication software.74 In addition to customizing the vocabulary, many augmentative and alternative communication devices and apps permit the visual appearance of symbols to be modified. Freedom to adjust the size of the symbols18,19,22 can be beneficial for users with low vision. Additionally, preexisting symbols can often be replaced with new selections from the Internet, personal photographs, or built-in symbol libraries.16,19,20,23,24,84-87 Replacing the symbol’s image with one that better represents a language concept to a user can improve learning and communication drastically.83 This customization inevitably limits the interuser transferability of symbol sets. Device personalization also now extends to voice output. In addition to offering a variety of realistic synthetic voice options,13,14,16-18,23,25-28,87 many apps and some devices provide the option of recording voice output.25,84-87 Some systems or apps even offer affective and expressive variants of the same voice, such as happy and sad18 or whining, whispering and shouting17,23 speech output alternatives.
Shifting From Dedicated to Integrated Communication Systems To meet the expanding scope of communication, many augmentative and alternative communication companies are now evolving their offerings from dedicated communication systems to systems that can be seamlessly integrated into the digital environs. Many of the devices produced by these companies can now be either purchased as dedicated speech generation systems or with additional computer capabilities,13,14,16,25,29 such as Internet browsing and word processing software. Manufacturers often also facilitate mobile phone functions (ie, texting, calling)16,25,26,30 and environmental control of infrared (IR) or Bluetooth-enabled household appliances (eg, televisions, DVD players).13-17,25-27,29 This new integrated option couples the expertise and technical support of established augmentative and alternative communication companies with the increased functionality and interconnectivity offered by mobile devices. However, in some jurisdictions, current health insurance generally only covers augmentative and alternative communication devices solely running communication software17,29,31 whereas mobile devices adapted for augmentative and alternative communication use are typically not covered by health plans.32 Nonetheless, these mobile solutions are significantly less expensive than the multifunctional or dedicated devices sold by augmentative and alternative communication companies. In other jurisdictions, there are emerging funding programs that will reimburse, at least partially, the cost
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of a generic mobile device (eg, iPad or iPod) equipped with a government-approved communication app.37 As an interesting alternative, the ComLinkProSlateÔ series34,38,42 provides a hybrid between traditional and mobile device–based high-tech communication aids. Devices within this series have the full features of a dedicated speech generation device, such as voice output modules and switch accessibility, but are loaded with one of several popular iOS communication apps. Furthermore, because they are dedicated speech-generating devices, they are fully funded by health insurance.34,38,42
Discussion Deriving full benefit from an access solution necessitates longterm adoption of the device. Unfortunately, abandonment of communication devices has traditionally been a significant concern. Major factors often implicated in device abandonment include an incomplete assessment of user abilities and context,11 lack of user and communication partner training, and a poor fit between the user’s abilities and the system’s characteristics.35 Recent trends in communication-based access solutions, however, may provide an opportunity to mitigate abandonment. Traditional access technologies based on mechanical switches are extremely difficult for some individuals with cerebral palsy to operate.36,50 This is an important cause of poor performance and subsequent abandonment. The increasing proliferation of new access technologies could potentially address this issue. The advent of access technologies based on eye gaze, arbitrary head or limb movements, nonspeech vocalizations, and facial expressions increases the possibility of offering access to each unique individual. However, the evidence for many of these technologies is not yet robust and largely based on case study or case series reports. Further, this proliferation of new access technologies does not come without challenges. As the range of available options grows, so too does the need for thorough, timely, and systematic assessment to identify the optimal technology for a given child. This should be a formal process that combines the opinions of and desired outcomes for parents, clinicians, and pediatric clients alike with objective measures of switch use and communication ability.11 Some recent work has focused on formalizing such protocols,11 invoking a multidisciplinary team that includes parents, teachers, speech-language pathologists, occupational therapists, and rehabilitation or clinical engineers. Additional research is still needed in this area. It is also important to recognize that the appropriate access solution may change over time. As children grow, they may require new functionality from their access solution, and may be able to master more complex augmentative and alternative communication systems. They may also desire to use their access solution in a wider variety of environments. These evolving requirements have traditionally been problematic because of the limited adaptability of augmentative and alternative communication devices. The increasing availability of highly flexible augmentative and alternative communication systems
(eg, apps for tablet and smart phones) should make it much easier to cope with such dynamic requirements. The significant reduction in cost also facilitates frequent switching between augmentative and alternative communication systems, so users will not be shackled to a device that no longer meets their needs, although clearly, cost is not the only enabler of augmentative and alternative communication system mastery. The shift in access solutions from specialized to general, integrated devices may promote the translation of device usage from institutions to the home environment. Moreover, the greater degree of social acceptance of smart phone and tablet-based augmentative and alternative communication devices over dedicated augmentative and alternative communication devices could also counter abandonment.69,74,81 Certain limitations to the current state of communication access solutions must be recognized. High-tech access solutions like those detailed within this review are not suitable for all situations and environments. Practical concerns like battery power and device portability typically limit the usage of hightech devices. Low-tech assistive technologies may address these issues, but may offer limited adaptability and scope of communication. High-tech devices for long-term usage are often susceptible to inadvertent activations.39 These shortcomings motivate a ‘‘total communication’’ approach, where assistive technologies are deployed in complementarity with other modes of communication.40 We recommend several future directions in assistive technology research for children with cerebral palsy. First, multiuser studies should be performed on emerging access technologies that have not yet been applied to individuals with cerebral palsy. These include surface microphones for detecting muscle contractions,41 the detection of vocalizations using microphones or surface EMG,43,90 and brain-computer interfaces based on electroencephalography or near-infrared spectroscopy.91-93 As existing research with these emerging modalities has been based on modest samples of children, a more extensive evidence base must be established. Second, more research must be devoted to the study of efficient communicative interaction in the context of severe disability. Caregivers have long criticized existing assistive technologies for slow and tiresome scanning protocols that frustrate pediatric users and communication partners alike, thereby heightening the risk of abandonment. Some worthwhile research and development foci may include deliberate departures from traditional single-switch scanning paradigms, such as continuous pointing gestures as invoked in Dasher94 and investigations to enhance instantaneous machine awareness of the human-machine interaction through, for example, the exploitation of event-related potentials on a single-trial basis.95-97
Conclusions This study has identified some emergent trends in access technologies and augmentative and alternative communication devices that are used in communicative access solutions for children with cerebral palsy. Access technologies have evolved from direct physical activation and simple mechanical switches
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to custom-placed sensors that are less dependent on gross motor control. Numerous access technologies have emerged, including eye-gaze tracking, thermal cameras, microphones, and pressure sensors. Augmentative and alternative communication devices have progressed from bulky electronic systems with limited message output to vocabulary-rich, highly customizable, portable alternatives. Augmentative and alternative communication devices are trending toward mobile and tablet applications that are more affordable, readily available, easier to use, and even socially acceptable. However, augmentative and alternative communication apps do require time to customize, and, with the numerous options now available, identifying the most suitable augmentative and alternative communication device for a given child is often a daunting task. Future research must focus on the development of more effective and intuitive user interfaces, validation of access technologies and augmentative and alternative communication devices with larger populations, and the development of a formal process for choosing the optimal access solution.
Key Take-Home Messages Access technologies are expanding, in earnest, beyond traditional mechanical switches. Technologies based on inertial sensing, machine vision and physiological signals are showing promise with small samples of individuals with cerebral palsy and other neurodevelopmental conditions. Augmentative and alternative communication systems are shifting from dedicated hardware to ubiquitous, socially appealing mobile devices and mainstream operating systems. In parallel, there has been a heavy precipitation of communication apps that provide enhanced device personalization (images, vocabulary, voice output, languages) at a fraction of the cost of traditional augmentative and alternative communication systems. Evidence for the effectiveness of these access technology and augmentative and alternative communication system developments is largely case-based at present, but mounting rapidly. In light of the above, the introduction of access technology ought to be considered for children and youth with at least nascent contingency awareness, even in the presence of sensory and/or severe motor impairments, which preclude the use of conventional mechanical switches. Author Contributions AM, SW, LS, and TZ conducted the literature search and wrote individual sections of the manuscript. TC conceptualized the manuscript, helped to consolidate the various pieces, edited manuscript drafts, and revised the manuscript according to reviewer comments.
Declaration of Conflicting Interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
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18. Proloquo2Go. Assist Ware Proloquo2Go. September-11-13. Available at: http://www.assistiveware.com/product/proloquo2go. Accessed October 26, 2013. 19. TalkRocket Go. TalkRocketGo MyVoice. 2012. Available at: http://myvoiceaac.com/app/talkrocketgo/. Accessed October 26, 2013. 20. Sono Flex. AAC iPhone iPad Android PC - Tobii SonoFlex. 2013. Available at: http://www.tobiisonoflex.com/. Accessed October 26, 2013. 21. Speech Button. Speech Button AAC App Wip It Up. 2013. Available at: http://www.wipitup.com/?page_id¼2. Accessed October 26, 2013. 22. Tobii C15, a communication device for speech and language. Tobii Technol. 2013. Available at: http://www.tobii.com/en/ assistive-technology/global/products/old-or-discontinued-products/ tobii-C15/. Accessed October 26, 2013. 23. Tango. Spectronics - Incl Learn Technol. Available at: http://www. spectronicsinoz.com/product/tango-2/. Accessed October 26, 2013. 24. Scene&Heard. Scene Heard Ther Box Ltd. 2013. Available at: http://therapy-box.co.uk/scene_and_heard.aspx. Accessed October 26, 2013. 25. Tobii Technology. Communication Unbound with Tobii I-Series. Tobii Technol. 2013. Available at: http://www.tobii.com/en/assistive-technology/north-america/products/hardware/tobii-i-series/. Accessed October 26, 2013. 26. Tellus 4. Jabbla. 2013. Available at: http://www.jabbla.com/ products.asp?itemID¼10. Accessed October 27, 2013. 27. DynaVox. DynaWrite 2.0 Talk, Type, Thrive! DynaVox Technol. 2013. Available at: http://ca.dynavoxtech.com/products/dynawrite/. Accessed October 27, 2013. 28. Lightwriter SL40. Toby Chruchill. 2011. Available at: http://www. toby-churchill.com/products/lightwriter-sl40/. Accessed October 27, 2013. 29. ECO2. PRC. 2013. Available at: https://store.prentrom.com/ product_info.php/cPath/11/products_id/53. Accessed October 26, 2013. 30. Accent 1000. PRC. 2013. Available at: https://store.prentrom. com/product_info.php/cPath/11/products_id/235. Accessed October 26, 2013. 31. Medicare coverage policy on speech-generating devices. Am Speech-Lang-Hear Assoc. Available at: http://www.asha.org/ practice/reimbursement/medicare/sgd_policy/. Accessed October 26, 2013. 32. White SC, McCarty J. Reimbursement for AAC Devices. ASHA Lead. 2011;16:3,7. 33. Tobii Technology AB: Tobii brings gaze interaction to tablet devices. Business Wire. September 19, 2013. 34. The ComLink ProSlate 10. FRS Cust Solut. 2011. Available at: http://www.frs-solutions.com/products/comlinks/proslates/Pro Slate_10. Accessed October 26, 2013. 35. Johnson JM, Inglebret E, Jones C, Ray J. Perspectives of speech language pathologists regarding success versus abandonment of AAC. Augment Altern Commun. 2006;22:85-99. 36. McNaughton D, Rackensperger T, Benedek-Wood E, Krezman C, Williams M, Light J. ‘‘A child needs to be given a chance to succeed’’: parents of individuals who use AAC describe the benefits
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53. Ann OC, Theng LB. Biometrics based assistive communication tool for children with special needs. In: 2011 7th International Conference on Information Technology in Asia (CITA 11). 2011:1-6. 54. Ann OC, Theng LB. Helping disabled people: the potentials of biometric information. Interact Technol Smart Educ. 2012;9: 153-170. 55. Memarian N, Blain-Moraes S, Chau T. Towards a physiological signal-based access solution for a non-verbal adolescent with severe and multiple disabilities. Dev Neurorehabil. 2013;1-8. 56. Lesperance A, Blain S, Chau T. An integrated approach to detecting communicative intent amid hyperkinetic movements in children. Augment Altern Commun. 2011;27:150-162. 57. Blain-Moraes S, Chau T. Challenges of developing communicative interaction in individuals with congenital profound intellectual and multiple disabilities. J Intellect Dev Disabil. 2012;37: 348-359. 58. Leung B, Brian JA, Chau T. Learning and mastery behaviours as risk factors to abandonment in a paediatric user of advanced single-switch access technology. Disabil Rehabil Assist Technol. 2013;8:426-433. 59. iTalk2 and iTalk2with Levels Communicators. Ablenet Inc. 2013. Available at: http://www.ablenetinc.com/Assistive-Technology/ Communication/iTalk2-and-iTalk2-with-Levels. Accessed October 27, 2013. 60. BIGmack Communicator. DynaVox Mayer-Johns. 2013. Available at: http://www.mayer-johnson.ca/bigmack-communicator. Accessed October 27, 2013. 61. LITTLEmack Communicator. DynaVox Mayer-Johns. 2013. Available at: http://www.mayer-johnson.ca/littlemack-communicator. Accessed October 27, 2013. 62. Talking Brix. DynaVox Mayer-Johns. 2013. Available at: http:// www.mayer-johnson.ca/talking-brix. Accessed October 27, 2013. 63. BIG Step-by-Step and LITTLE Step-by-Step Communicators. Ablenet Inc. 2013. Available at: http://www.ablenetinc.com/ Assistive-Technology/Communication/BIG-Step-by-Step-LITTLEStep-by-Step. Accessed October 27, 2013. 64. BIG Step-byStep with Levels Communicator. Ablenet Inc. 2013. Available at: http://www.ablenetinc.com/Assistive-Technology/ Communication/BIG-LITTLE-Step-by-Step-with-Levels. Accessed October 27, 2013. 65. Tobii S32 Speech Device. Tobii Technol. 2013. Available at: http://www.tobii.com/en/assistive-technology/global/products/ hardware/tobii-s32/. Accessed October 27, 2013. 66. Go Talk 9þ. DynaVox Mayer-Johns. 2013. Available at: http:// www.mayer-johnson.com/gotalk-9. Accessed October 27, 2013. 67. SuperTalker Progressive Communicator. Ablenet Inc. 2013. Available at: http://www.ablenetinc.com/Assistive-Technology/ Communication/SuperTalker. Accessed October 27, 2013. 68. QuickTalker Family of Communication Devices. Ablenet Inc. 2013. Available at: http://www.ablenetinc.com/Assistive-Tech nology/Communication/QuickTalker. Accessed October 27, 2013. 69. Light J, Drager K. AAC technologies for young children with complex communication needs: state of the science and future research directions. Augment Altern Commun. 2007;23:204-216.
70. Baxter S, Enderby P, Evans P, Judge S. Interventions using hightechnology communication devices: a state of the art review. Folia Phoniatr Logop Off Organ Int Assoc Logop Phoniatr IALP. 2012;64:137-144. 71. Judge S, Friday M. Ambiguous keyboards for AAC. J Assist Technol. 2011;5:249-256. 72. Deruyter F, McNaughton D, Caves K, Bryen DN, Williams MB. Enhancing AAC connections with the world. Augment Altern Commun. 2007;23:258-270. 73. Radomski MV, Latham CAT. Occupational Therapy for Physical Dysfunction. Philadelphia, PA: Lippincott Williams & Wilkins; 2008. 74. McNaughton D, Light J. The iPad and mobile technology revolution: benefits and challenges for individuals who require augmentative and alternative communication. Augment Altern Commun. 2013;29:107-116. 75. Bradshaw J. The use of augmentative and alternative communication apps for the iPad, iPod and iPhone: an overview of recent developments. Tizard Learn Disabil Rev. 2013;18:31-37. 76. Shane HC, Blackstone S, Vanderheiden G, Willams M, DeRuyter F. Using AAC technology to access the world. Assist Technol. 2012;24:3-13. 77. Anonymous. AssistiveWare; Proloquo2Go iPhone app shakes up assistive technology industry. Life Sci Wkly. 2009. 78. Dixon D. The future of apps in the classroom. ASHA Lead. 2011; 16:30. 79. Tobii Technology. 7 steps of funding. Tobii Technol. 2013. Available at: http://www.tobii.com/en/assistive-technology/north-amer ica/funding/funding-for-your-device/. Accessed October 26, 2013. 80. Mcnaughton D, Bryen DN. AAC technologies to enhance participation and access to meaningful societal roles for adolescents and adults with developmental disabilities who require AAC. Augment Altern Commun. 2007;23:217-229. 81. Hodge S. Why is the potential of augmentative and alternative communication not being realized? Exploring the experiences of people who use communication aids. Disabil Soc. 2007;22:457-471. 82. Light J, McNaughton D. The changing face of augmentative and alternative communication: past, present, and future challenges. Augment Altern Commun. 2012;28:197-204. 83. Light J, McNaughton D. Supporting the communication, language, and literacy development of children with complex communication needs: state of the science and future research priorities. Assist Technol. 2012;24:34-44. 84. MyTalkTools Mobile. MyTalk Mob Work. 2013. Available at: http://www.mytalktools.com/dnn/Products.aspx. Accessed October 26, 2013. 85. GoTalk Now. GoTalk Attain Fam. 2013. Available at: http://www. attainmentfamily.com/GoTalkNow. Accessed October 26, 2013. 86. SoundingBoard. AAC App iPhone iTouch iPad Sound AbleNet. 2013. Available at: http://www.ablenetinc.com/Assistive-Technology/Communication/SoundingBoard. Accessed October 26, 2013. 87. TalkingTILES. TalkingTILES Mozzaz. August-27-13. Available at: http://mozzaz.com/index.php/products/talkingtiles. Accessed October 26, 2013. 88. Nakamura K, Newell A, Alm N, Waller A. How do members of different language communities compose sentences with a
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93. Hoffmann U, Vesin J-M, Ebrahimi T, Diserens K. An efficient P300-based brain-computer interface for disabled subjects. J Neurosci Methods. 2008;167:115-125. 94. Ward DJ, MacKay DJC. Fast hands-free writing by gaze direction. arXiv: cs/0204030. 2002. Available at: http://arxiv.org/abs/ cs/0204030. Accessed January 5, 2014. 95. Zeyl TJ, Chau T. A case study of linear classifiers adapted using imperfect labels derived from human event-related potentials. Pattern Recognit Lett. 2014;37:54-62. 96. Chavarriaga R, Millan JDR. Learning from EEG error-related potentials in noninvasive brain-computer interfaces. IEEE Trans Neural Syst Rehabil Eng Publ IEEE Eng Med Biol Soc. 2010; 18:381-388. 97. Yin E, Zhou Z, Jiang J, Chen F, Liu Y, Hu D. A speedy hybrid BCI spelling approach combining P300 and SSVEP. IEEE Trans Biomed Eng. 2013; doi:10.1109/TBME.2013.2281976.
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Trends in Communicative Access Solutions for Children With Cerebral Palsy
Journal of Child Neurology 2014, Vol. 29(8) 1108-1118 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0883073814534320 jcn.sagepub.com
Andrew Myrden, MASc1,2, Larissa Schudlo, MASc1,2, Sabine Weyand, MASc1,2, Timothy Zeyl, MASc1,2, and Tom Chau, PhD, PEng1,2
Abstract Access solutions may facilitate communication in children with limited functional speech and motor control. This study reviews current trends in access solution development for children with cerebral palsy, with particular emphasis on the access technology that harnesses a control signal from the user (eg, movement or physiological change) and the output device (eg, augmentative and alternative communication system) whose behavior is modulated by the user’s control signal. Access technologies have advanced from simple mechanical switches to machine vision (eg, eye-gaze trackers), inertial sensing, and emerging physiological interfaces that require minimal physical effort. Similarly, output devices have evolved from bulky, dedicated hardware with limited configurability, to platform-agnostic, highly personalized mobile applications. Emerging case studies encourage the consideration of access technology for all nonverbal children with cerebral palsy with at least nascent contingency awareness. However, establishing robust evidence of the effectiveness of the aforementioned advances will require more expansive studies. Keywords cerebral palsy, children, communication, access technology Received April 02, 2014. Received revised April 02, 2014. Accepted for publication April 03, 2014.
It is estimated that 40% of children with cerebral palsy, particularly those at Gross Motor Function Classification System level IV or V, experience some degree of difficulty with expressive communication.1 Communication restrictions have been associated with delayed language development2 and reduction in peer interactions, self-esteem, and quality of life.1,3 Consequently, children, parents, and health care providers have identified communication enhancement as a high-priority therapy goal in cerebral palsy.1,3,4 Indeed, functional communication fosters independence, reveals a child’s true developmental status, and allows a child to be involved in his or her care.5 Children with cerebral palsy who have complex communication needs can benefit from access solutions that provide alternative means of communication. As shown in Figure 1, a communication access solution has 3 components—the access pathway, a signal processing unit, and the augmentative and alternative communication system.3,6 The access pathway refers to the input used to control the system, which traditionally might be direct (eg, touching the augmentative and alternative communication device’s screen to select the object of interest) or indirect (eg, waiting for an on-screen keyboard to scan to the desired letter and then contacting one or more mechanical switches external to the augmentative and alternative communication
device to make a selection). The former is user-paced whereas the latter is system-paced. The signal processing unit embodies an algorithm that processes the user input. Collectively, the access pathway and signal processing unit constitute the access technology.6 The augmentative and alternative communication system refers to the user interface, which can be grouped into one of 3 categories: low, mid, and high-tech. Low-tech augmentative and alternative communication systems include nonelectronic devices such as printed communication boards. Mid-tech augmentative and alternative communication systems include electronic devices with a single static display and/or a scanning system with one level of choice. Finally, high-tech
1
Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Road, Toronto, Ontario, Canada 2 Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, Canada Corresponding Author: Tom Chau, PhD, PEng, Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Road, Toronto, Ontario M4G 1R8, Canada. Email: [email protected]
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Figure 1. Schematic of a communication access solution. The access technology consists of an access pathway and signal processing unit.
augmentative and alternative communication systems have dynamic displays and/or several layers of choices.3 Early introduction of access solutions for children with cerebral palsy can enable communication and promote the development of spoken language.7 Sevcik and colleagues8(p1328) proposed that access solutions should be a ‘‘first line of intervention’’ that can ‘‘set the stage for further language and communication development’’ for young children with communication difficulties. Nonverbal children with cerebral palsy can interact with their communication partners by using gestures or vocalizations. These forms of communication require some degree of motor control on the part of the child. On the other hand, interpretation of such communicative attempts requires that the communication partner possess a high degree of familiarity with the child, including his or her behavioral idiosyncrasies, movement patterns,9 personal preferences,10 and daily routine. Successful communication also necessitates close attention to subtle physical cues, such as changes in the child’s body posture, eye gaze, facial expressions, vocalizations, and muscle tone. Clearly, such stringent prerequisites limit the potential number of functional communication partners for the child, as each partner must be intimately attuned to the child’s temperament and all the aforementioned behaviors. Access technologies remove some of this dependence on communication partners, allowing children to independently control augmentative and alternative communication devices and thereby develop communication abilities in a variety of social environments.10,11 This article presents a scoping review of the current trends in access solutions for children with cerebral palsy, based on both scientific and gray literature, and the implications for clinical practice. We present the search methods, search results arranged by access technology and augmentative and alternative communication device, and a brief discussion, including emergent research.
Methods Using the keywords cerebral palsy, communication, technology, and children (synonyms and variations thereof), we searched the following databases: Web of Science, Google Scholar, Scopus, ProQuest, and Compendex databases, for journal articles published between 2008 and October 2013. The search yielded 61 candidate articles. This list was further filtered down to 20 articles that deployed a technologybased communication solution, relating to the production of speech or text, for at least 1 young person (18 years of age or younger) with cerebral palsy. In addition, we also combed the gray literature by initially searching ProQuest with the terms communication, technology, and augmentative and alternative communication in all search fields. All information sources (blogs, podcasts, trade journals, magazines, conference proceedings, etc) except dissertations and theses were included. The search yielded 3921 items, which were then screened for relevancy to the topic area (ie, augmentative and alternative communication technology for children with cerebral palsy), yielding 37 different access solutions. For those that involved products and apps that had been released since 2008, we further visited the manufacturer or vendor websites as available to collect additional information.
Results Our scan of the scientific and gray literature identified a changing landscape in terms of both access technologies and augmentative and alternative communication devices. The key findings will be presented under these 2 main categories below.
Access Technologies Over the past several decades, the proliferation of consumer electronics has enabled many new means of communication for children with cerebral palsy who are nonverbal, which roughly constitutes a quarter of the pediatric cerebral palsy population.12 For those with some controlled movement, standard (eg, trackballs, joysticks, mice, and keyboards) or adapted (eg, mechanical switches) input devices can facilitate access
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Table 1. High-Tech Augmentative and Alternative Communication Devices Currently on the Market (Released Since 2008). Device
Description
Release date
Tobii® I-SeriesI12,13 I1513 AccentÔ 1000,14 120015 ComLinkProSlate 4Ô,16 8Ô,17 10Ô18
Symbol-grid system and text-to-speech Symbol-grid system Load with choice of iOS app such as Proloquo2go, SonoFlex and others. Symbol-grid system and text-to-speech
May 2013 November 2012 4, 8: July 2011, 10: November 2012
Symbol-grid system Wearable augmentative and alternative communication system—converts ComLinkdevice or iPod/iPad to wearable augmentative and alternative communication device with speaker Symbol-grid system Symbol-grid system and text-to-speech Symbol-grid system and text-to-speech Symbol-grid system and text-to-speech Symbol-list system and text-to-speech Text-to-speech Text-to-speech Text-to-speech Tablet with built-in eye gaze
January 2012 July 2011
ComLinkLT(3G)Ô,19 ComLinkLT(3G)Ô with Enable Eyes20 ECO221 SoundPODÔ22
PowerBox 723 Tobii® C-Series C8,24 C12,25 C1526 DynaVox MaestroÔ27 DynaVox Xpress Ô 2.028 Tango!29 Lightwriter® SL4030 DynaWriteÔ 2.031 Tellus 432 Sahara EyeSlate33
January 2012
June 2011 8, 12: January 2009, 15: January 2011 October 2010 August 2010 February 2009 June 2013 June 2011 2010 June 2013
Table 2. Commercially Available Augmentative and Alternative Communication Apps Released Since 2008. App
Description
Compatible platforms
TalkingTILES34
Symbol-grid system Access method: touch Symbol-grid system and text-to-speech Access methods: touch, adaptive switch, adjustable direct touch Symbol-list system, photo story Access methods: touch, keyboard, Bluetooth switch Symbol-grid system Access methods: touch, Bluetooth switch Symbol-grid system and text-to-speech Access methods: touch Symbol-grid system, photo story Access methods: touch, another iPad/ iPod with Attainment Switch39 app, Bluetooth switch Photo story, add videos and audio to personal photos Access methods: Bluetooth switch, Therapy Box Switch Box, ‘‘touch anywhere’’ scanning Symbol-grid system. Simple vocabulary, not customizable Access method: touch Symbol-grid system Access method: touch, Bluetooth switch Text-to-speech Accommodates shaky or inexact key selections. Access method: touch Text-to-speech Access method: touch
iOS and Android
$299.99
iOS
$219.99
Proloquo2go®35 TalkRocketGo36 MyTalkTools Mobile37 Sono Flex11 GoTalk NOW38 Scene&Heard40 Speech Button41 SoundingBoardÔ42 RocketKeys43 Verbally44
to communication via specialized augmentative and alternative communication hardware (Table 1) or augmentative and alternative communication software applications (Table 2) on generic computing platforms. For those capable of deictic gestures (eg, pointing), capacitive and resistive touch screen technologies
Cost (USD)
iOS and Android
$99.99
iOS
$99.99
iOS, Android, PCs, Kindle Fire, devices with Tobii Communicator iOS (iPad only)
$99.99 $79.99
iOS
$49.99
iOS
$7.99
iOS
Free
iOS and Android
iOS (iPad only)
$159.99
Free
offer direct access to communication devices and applications (eg, Noren et al9). Likewise, individuals who can control intraoral air pressure (eg, via buccinator muscles and diaphragm) may be able to operate a ‘‘sip and puff’’ switch. These motor-based access methods can be effective when
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Table 3. Recent Studies Investigating Access Technologies for Children With Cerebral Palsy.
Category
Physiological input
Access pathway
Functional activity
No. of children with cerebral palsy Authors
Skin temperature, heart Autonomic rate, respiration nervous system signals
Temperature, blood volume pulse, Communicate emotional state and electrodermal activity sensors and respiration belt
1
Memarian51
Hand/foot
Video camera, image processing
4
Gonzalez52
Movement of hand and foot, Hand movements,
Control cursor
Eyes
Select letter from on-screen keyboard Hyperkinetic movement Accelerometer on upper limbs, head Communicate preference Facial expression, Video camera, image processing Communicate emotional state Tongue protrusion, Video camera Select graphical icon Mouth opening Thermal camera Select letter from on-screen keyboard Eye Gaze Eye tracker Select graphical icon
Head
Head movement,
Vocalization
Head movement, Head movement Humming
Mouth/Face
Pressure sensing microswitch
Accelerometer, gyroscope, magnetometer Video camera, image processing Gyroscope Accelerometer on throat
they cater to the specific capabilities of an individual with cerebral palsy.45-49 However, for many children with cerebral palsy, these access technologies are not plausible because of difficulties with switch targeting, mounting and positioning, activation with kinetic sufficiency, and release following activation.50
Inertial, Computer Vision, and Physiological Access Pathways With the emergence of light weight, cost-effective sensors, advances in mobile computing hardware and new developments in pattern recognition software, individualized access technologies incorporating custom-placed sensors and personalized signal processing have become increasingly prominent in scientific literature. Table 3 provides an overview of some recent literature on state-of-the art access technologies that have been tested with modest samples of children with cerebral palsy. These technologies include video and thermal cameras that can detect and interpret limb movements, head motion and facial expressions; pressure sensors that detect switch depression with individual-specific sensitivity; magnetometers, gyroscopes, and accelerometers that sense position, angular velocity, and vibration for the purpose of detecting limb movement and vocalizations; and eye-gaze trackers that enable cursor control and icon selection. Some of these technologies are now commercially available. For example, many augmentative and alternative communication companies now offer eye gaze as an alternative access method, with the possibility of interfacing to a tablet computer.33,51
Control cursor Control cursor Control cursor Select letter from on-screen keyboard
1 10
Lancioni53,54 Stasolla55 Lesperance56 Ann44,57
1 1
Leung12 Memarian58
5
Amantis59
2,3
Raya60,61
1,1,3
4 2 2
Gonzalez52 Mukherjee62 Falk63
Enabling Passive Communication In addition to active communication, where the user explicitly attempts to express himself or herself, access technologies are also being developed for passive communication. For the subset of nonverbal children who may not be able to initiate communication or respond to questions using an access pathway (ie, typically those for whom contingency awareness remains ambiguous), it is believed that enabling passive communication, that is, the automatic decoding of affective state, response to environmental stimuli, and/or personal preference may enhance their quality of care and ultimately quality of life.52 Such information could inform the interaction with these children, including the choice of therapeutic activities, toys, and food. For this goal, researchers have investigated the usage of video cameras and various physiological sensors to track changes in skin temperature, heart activity, electrodermal activity, respiration, and facial expressions in response to certain stimuli and environmental contexts.53-55 Accelerometry has also been exploited for the automatic decoding of preferences of nonverbal children with hyperkinetic movements.56 Although the above-cited studies present some promising early case evidence, the general effectiveness of these passive access modalities remains to be proven. A fundamental challenge in establishing effectiveness is the absence of ground truth; that is, these children and youth cannot confirm the verity of the inferred state or response, and often a subjective proxy validation (eg, parent or familiar caregiver) is all that is available. The fallibility of such proxy validations is highlighted by a recent study that unveiled potential inconsistencies between parental interpretation of the behavioral manifestations of preference
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of a nonverbal, contingently unaware adolescent with cerebral palsy, and quantitative measures of his autonomic responses.57
Outstanding Challenges Although the number of available access technologies has increased, evidence of their clinical effectiveness is, for the most part, only emerging. Most studies in the scientific literature have either been case studies or have, often for pragmatic reasons, tested a very small sample of pediatric participants with cerebral palsy. Nonetheless, studies to date have shown, on a small sample basis, that advanced access technologies have the ability to reduce physical exertion, increase communication efficiency, and increase accuracy over that achievable with existing input methods (eg, Falk44). However, recently proposed access technologies are not immune to accidental activation by involuntary movements (eg, primitive reflexes) or voluntary movements that are not intended to control the access solution.45 A classic depiction of this dilemma is the so-called Midas Touch predicament, in which a targeted access site bears both a technology-control intention (eg, eye gaze to move cursor) and a no-tech expressive communication function (eg, vertical eye movements to express yes or no to a communication partner). These false activations are of particular concern because of their tendency to cause unpredictable behavior in the access solution, potentially leading to frustration, learned helplessness, and abandonment.58 It is difficult to compare accuracies of various access technologies across case studies, as they are largely dependent on the abilities of the participant, the appropriateness of the prescribed access technology for the individual, and the magnitude and quality of training provided to the user and his or her communication partners.11
Augmentative and Alternative Communication Devices Recent Developments in Mid-Tech Communication Solutions Traditionally, the most common electronic augmentative and alternative communication devices were mid-tech, an umbrella term encompassing static, single, and multimessage speechgenerating devices that produce a fixed number of messages. The simplest are those that play recorded voice messages with the push of a button. Although these devices were typically single- or dual-message communicators, like the iTalk2Ô,59 BIG/ LITTLEmackÔ,60,61 and TalkingBrixÔ,62 there are now variants that offer an unlimited number of output messages that play in sequence, such as BIG/LITTLE Step-by-StepÔ,63 or even multiple sequences, as in the BIG/LITTLE Step-by-Step with Levels.64 For multimessage output, static electronic communication boards offer greater flexibility. Many boards, such as the Tobii® S32,65 GoTalk Series,66 SuperTalkerÔ Progressive Communicator,67 and the QuickTalkerÔ Family of Communication Devices,68 contain multiple locations that play voice
messages when selected. Some devices, such as the Tobii S32 Scan, GoTalk, and SuperTalker, also use custom-made interchangeable overlays that allow different recorded messages to play with each overlay. Other boards, such as the QuickTalker series, include multiple levels, with each level producing a new set of output messages. Although this eliminates the need for multiple overlays, the number of messages is limited, and the images associated with each frame do not change with the audio. Additionally, these boards all support touch input, but do not always accommodate switch inputs. These mid-tech augmentative and alternative communication devices are readily available. They are easy to use and learn, making them particularly suitable for young children.69 Although they can be portable and lightweight, they are generally bulkier and less versatile than high-tech alternatives.
Migration to Mobile Platforms: High-Tech Communication Solutions High-tech options have become prevalent over the past 20 years,70 as technological advances have allowed the design of dynamic augmentative and alternative communication devices. Rather than producing a single output for each input, these devices are coded, permitting multiple possible outputs for a limited number of inputs.71 In comparison to static boards, dynamic screen communication devices provide a larger vocabulary to the user at one time, enabling more natural and responsive communication. Until recently, the market for high-tech, dynamic augmentative and alternative communication devices was dominated by a small number of companies.72 These companies produced a limited number of dedicated systems, or systems that could only be used for communication.73 However, because of the mobile technology revolution, the use of mobile smart phones and tablets for augmentative and alternative communication has become widespread.74-76 This adaptation of mainstream hardware has created a significant paradigm shift in high-tech augmentative and alternative communication devices, as these popular communication tools offer several advantages over traditional systems, including cost,75-78 ease of use,74,75,77 availability,79 transportability,75,76,80 and social acceptance.69,74,75,81 Additionally, these multifunctional mobile devices provide access to mainstream phone applications, such as text messaging, e-mail, and internet browsing, which have become essential aspects of communication.76,82,83 Table 1 presents a list of high-tech augmentative and alternative communication systems that are commercially available at the time of writing.
Growing Abundance of Apps Because of the economic and social appeal of deploying mainstream consumer technology for communication, there has been a recent surge in the number of mobile augmentative and alternative communication applications, or ‘‘apps.’’74,75 Assistive communication apps are currently available for a variety of platforms including Android, Windows, and most popularly,
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iOS (Apple Inc’s mobile operating system for iPods, iPhones, and iPads).78 Although augmentative and alternative communication users are now afforded a diversity of cost-effective, easily attainable options, most apps have been developed by programmers who do not necessarily possess knowledge in language development.74,82 Consequently, not all apps represent language concepts in a manner that is conducive to learning and optimizing communication. Unlike devices purchased from large augmentative and alternative communication companies,79 these apps can be easily purchased without the input of a clinician. Thus, failure to reap the anticipated benefits of augmentative and alternative communication may simply be due to a mismatch between the specific app’s functions and the individual user’s needs. Furthermore, many apps do not support connections to alternative access technologies. Unfortunately, minimal research has focused on improving the design of augmentative and alternative communication apps, even though simple design changes can often substantially impact communication performance.83 Many app purchases are currently driven by hype, rather than an understanding of what is required to optimize communication for a specific user, information typically derived from a systematic, multidisciplinary assessment of the user’s needs and abilities.76 Table 2 presents an abbreviated list of some popular augmentative and alternative communication apps.
Enhanced Personalization Many augmentative and alternative communication devices and apps are now highly customizable. Features that can be personalized include vocabulary content and organization, visual appearance, and audio output. This flexibility allows the communication aid to be tailored to a specific user. However, device customization can be very time-consuming,77 especially for apps that require the creation of all graphics and communication pages from scratch.84-86 Nonetheless, apps are typically more intuitive to program than dedicated communication systems.77 Additionally, there is growing multilingual support within augmentative and alternative communication apps. At the time of this writing, some apps (eg, TalkingTILES87) already provide more than 40 different language alternatives and accommodate non-English symbols. Indeed, the incorporation of language-specific grammar has been identified as a general principle for ensuring clarity of meaning in non-English augmentative and alternative communication systems.88 Most augmentative and alternative communication systems employ symbol-based communication, in which symbols (that produce spoken words or phrases when selected) are organized into grids or lists. To continuously customize the user’s vocabulary, typically, new words or phrases can be added, as needed, and grouped topically, to form communication pages.13-20,84-87,89 Pages can also link to other groups of symbols or pages to provide more extensive organization. This allows caregivers, teachers, and clinicians to personalize the system and quickly respond to changing communication needs. However, complex organizations that require navigation through multiple
screens to locate the desired symbol can be overwhelming for the user,69,83 especially for young children or individuals with cognitive impairments. Augmentative and alternative communication layouts that use simple, sequential navigation though communication pages may be more appropriate for these individuals.21,86 The focus should be on strengthening communication and language concepts rather than simply exploiting technological advancements to enhance the complexity of augmentative and alternative communication software.74 In addition to customizing the vocabulary, many augmentative and alternative communication devices and apps permit the visual appearance of symbols to be modified. Freedom to adjust the size of the symbols18,19,22 can be beneficial for users with low vision. Additionally, preexisting symbols can often be replaced with new selections from the Internet, personal photographs, or built-in symbol libraries.16,19,20,23,24,84-87 Replacing the symbol’s image with one that better represents a language concept to a user can improve learning and communication drastically.83 This customization inevitably limits the interuser transferability of symbol sets. Device personalization also now extends to voice output. In addition to offering a variety of realistic synthetic voice options,13,14,16-18,23,25-28,87 many apps and some devices provide the option of recording voice output.25,84-87 Some systems or apps even offer affective and expressive variants of the same voice, such as happy and sad18 or whining, whispering and shouting17,23 speech output alternatives.
Shifting From Dedicated to Integrated Communication Systems To meet the expanding scope of communication, many augmentative and alternative communication companies are now evolving their offerings from dedicated communication systems to systems that can be seamlessly integrated into the digital environs. Many of the devices produced by these companies can now be either purchased as dedicated speech generation systems or with additional computer capabilities,13,14,16,25,29 such as Internet browsing and word processing software. Manufacturers often also facilitate mobile phone functions (ie, texting, calling)16,25,26,30 and environmental control of infrared (IR) or Bluetooth-enabled household appliances (eg, televisions, DVD players).13-17,25-27,29 This new integrated option couples the expertise and technical support of established augmentative and alternative communication companies with the increased functionality and interconnectivity offered by mobile devices. However, in some jurisdictions, current health insurance generally only covers augmentative and alternative communication devices solely running communication software17,29,31 whereas mobile devices adapted for augmentative and alternative communication use are typically not covered by health plans.32 Nonetheless, these mobile solutions are significantly less expensive than the multifunctional or dedicated devices sold by augmentative and alternative communication companies. In other jurisdictions, there are emerging funding programs that will reimburse, at least partially, the cost
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of a generic mobile device (eg, iPad or iPod) equipped with a government-approved communication app.37 As an interesting alternative, the ComLinkProSlateÔ series34,38,42 provides a hybrid between traditional and mobile device–based high-tech communication aids. Devices within this series have the full features of a dedicated speech generation device, such as voice output modules and switch accessibility, but are loaded with one of several popular iOS communication apps. Furthermore, because they are dedicated speech-generating devices, they are fully funded by health insurance.34,38,42
Discussion Deriving full benefit from an access solution necessitates longterm adoption of the device. Unfortunately, abandonment of communication devices has traditionally been a significant concern. Major factors often implicated in device abandonment include an incomplete assessment of user abilities and context,11 lack of user and communication partner training, and a poor fit between the user’s abilities and the system’s characteristics.35 Recent trends in communication-based access solutions, however, may provide an opportunity to mitigate abandonment. Traditional access technologies based on mechanical switches are extremely difficult for some individuals with cerebral palsy to operate.36,50 This is an important cause of poor performance and subsequent abandonment. The increasing proliferation of new access technologies could potentially address this issue. The advent of access technologies based on eye gaze, arbitrary head or limb movements, nonspeech vocalizations, and facial expressions increases the possibility of offering access to each unique individual. However, the evidence for many of these technologies is not yet robust and largely based on case study or case series reports. Further, this proliferation of new access technologies does not come without challenges. As the range of available options grows, so too does the need for thorough, timely, and systematic assessment to identify the optimal technology for a given child. This should be a formal process that combines the opinions of and desired outcomes for parents, clinicians, and pediatric clients alike with objective measures of switch use and communication ability.11 Some recent work has focused on formalizing such protocols,11 invoking a multidisciplinary team that includes parents, teachers, speech-language pathologists, occupational therapists, and rehabilitation or clinical engineers. Additional research is still needed in this area. It is also important to recognize that the appropriate access solution may change over time. As children grow, they may require new functionality from their access solution, and may be able to master more complex augmentative and alternative communication systems. They may also desire to use their access solution in a wider variety of environments. These evolving requirements have traditionally been problematic because of the limited adaptability of augmentative and alternative communication devices. The increasing availability of highly flexible augmentative and alternative communication systems
(eg, apps for tablet and smart phones) should make it much easier to cope with such dynamic requirements. The significant reduction in cost also facilitates frequent switching between augmentative and alternative communication systems, so users will not be shackled to a device that no longer meets their needs, although clearly, cost is not the only enabler of augmentative and alternative communication system mastery. The shift in access solutions from specialized to general, integrated devices may promote the translation of device usage from institutions to the home environment. Moreover, the greater degree of social acceptance of smart phone and tablet-based augmentative and alternative communication devices over dedicated augmentative and alternative communication devices could also counter abandonment.69,74,81 Certain limitations to the current state of communication access solutions must be recognized. High-tech access solutions like those detailed within this review are not suitable for all situations and environments. Practical concerns like battery power and device portability typically limit the usage of hightech devices. Low-tech assistive technologies may address these issues, but may offer limited adaptability and scope of communication. High-tech devices for long-term usage are often susceptible to inadvertent activations.39 These shortcomings motivate a ‘‘total communication’’ approach, where assistive technologies are deployed in complementarity with other modes of communication.40 We recommend several future directions in assistive technology research for children with cerebral palsy. First, multiuser studies should be performed on emerging access technologies that have not yet been applied to individuals with cerebral palsy. These include surface microphones for detecting muscle contractions,41 the detection of vocalizations using microphones or surface EMG,43,90 and brain-computer interfaces based on electroencephalography or near-infrared spectroscopy.91-93 As existing research with these emerging modalities has been based on modest samples of children, a more extensive evidence base must be established. Second, more research must be devoted to the study of efficient communicative interaction in the context of severe disability. Caregivers have long criticized existing assistive technologies for slow and tiresome scanning protocols that frustrate pediatric users and communication partners alike, thereby heightening the risk of abandonment. Some worthwhile research and development foci may include deliberate departures from traditional single-switch scanning paradigms, such as continuous pointing gestures as invoked in Dasher94 and investigations to enhance instantaneous machine awareness of the human-machine interaction through, for example, the exploitation of event-related potentials on a single-trial basis.95-97
Conclusions This study has identified some emergent trends in access technologies and augmentative and alternative communication devices that are used in communicative access solutions for children with cerebral palsy. Access technologies have evolved from direct physical activation and simple mechanical switches
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to custom-placed sensors that are less dependent on gross motor control. Numerous access technologies have emerged, including eye-gaze tracking, thermal cameras, microphones, and pressure sensors. Augmentative and alternative communication devices have progressed from bulky electronic systems with limited message output to vocabulary-rich, highly customizable, portable alternatives. Augmentative and alternative communication devices are trending toward mobile and tablet applications that are more affordable, readily available, easier to use, and even socially acceptable. However, augmentative and alternative communication apps do require time to customize, and, with the numerous options now available, identifying the most suitable augmentative and alternative communication device for a given child is often a daunting task. Future research must focus on the development of more effective and intuitive user interfaces, validation of access technologies and augmentative and alternative communication devices with larger populations, and the development of a formal process for choosing the optimal access solution.
Key Take-Home Messages Access technologies are expanding, in earnest, beyond traditional mechanical switches. Technologies based on inertial sensing, machine vision and physiological signals are showing promise with small samples of individuals with cerebral palsy and other neurodevelopmental conditions. Augmentative and alternative communication systems are shifting from dedicated hardware to ubiquitous, socially appealing mobile devices and mainstream operating systems. In parallel, there has been a heavy precipitation of communication apps that provide enhanced device personalization (images, vocabulary, voice output, languages) at a fraction of the cost of traditional augmentative and alternative communication systems. Evidence for the effectiveness of these access technology and augmentative and alternative communication system developments is largely case-based at present, but mounting rapidly. In light of the above, the introduction of access technology ought to be considered for children and youth with at least nascent contingency awareness, even in the presence of sensory and/or severe motor impairments, which preclude the use of conventional mechanical switches. Author Contributions AM, SW, LS, and TZ conducted the literature search and wrote individual sections of the manuscript. TC conceptualized the manuscript, helped to consolidate the various pieces, edited manuscript drafts, and revised the manuscript according to reviewer comments.
Declaration of Conflicting Interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
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