An Integrated Approach to Detecting Communicative Intent Amid
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01 Augmentative and Alternative Communication, 2011; 27(3): 150–162 Copyright © 2011 International Society for Augmentative and Alternative Communication ISSN 0743-4618 print/ISSN 1477-3848 online November DOI: 10.3109/07434618.2011.614640 2010 RESEARCH ARTICLE 22 An Integrated Approach to Detecting Communicative Intent Amid July Hyperkinetic Movements in Children 2011 ANDREA LESPERANCE, Stefanie BLAIN & TOM Chau* 11 University of Toronto and Holland Bloorview Kids Rehabilitation Hospital, Toronto August Abstract 2011 Children with hyperkinetic movement (HKM) often have limited access to traditional augmentative and alternative communica- tion technologies (e.g., mechanical switches). To seek a communication solution for these children, this study explored the possibil- ity that discernable biomechanical patterns, related to preference, exist amid HKM. We deployed a unified approach to analyse a Augmentative and Alternative Communication child’s movements, fusing caregiver and clinician observations with quantitative data (accelerations of the upper extremities). Two case studies were examined. In both, the accelerometer data identified preference at adjusted accuracies statistically above chance using a linear discriminant classifier. Visually, communicative movement patterns were identified in the first child (κ = 0.25-0.27) 10.3109/07434618.2011.614640 but not in the second child (κ = 0.03-0.11). Implications of this study include possible enhancement in communication and inde- pendence for these children. 2011 Keywords: Communication; Accelerometer; Observational analysis; Hyperkinetic movement; Paediatric 3 Introduction 150 Children with cerebral palsy commonly have a Hyperkinetic movement (HKM) is an excess of uncon- discrepancy between their expressive and receptive lan- For personal use only. trolled movement. In the paediatric population, HKM guage skills. The expressive language skills, or the child’s 162 is typically the result of an injury to or abnormal func- ability to verbally communicate is often hindered, while tion of the basal ganglia, cerebellum, or cerebral cortex, the child’s ability to understand language remains intact © 2011 International Society for Augmentative and most frequently associated with dyskinetic cerebral (Byrne et al., 2001; Pirila et al., 2007). A recent longi- Alternative Communication palsy (DCP) (Fahn & Jankovic, 2007; Lebiedowska, tudinal study of children with cerebral palsy found that 0743-4618 Gaebler-Spira, Burns, & Fisk, 2004). DCP affects 0.15 85% (11/13) of the children with a GMFCS level IV to 0.25 per 1000 children in Western countries (Sanger, and 100% (18/18) of those with a GMFCS level V had 2006) and is a sub-classification of cerebral palsy (CP), significantly lower communicative means compared to 1477-3848 in which motor impairments are secondary to anoma- children with typical development (Voorman, Dallmei- lies or lesions in the brain during early development jer, Van Eck, Schuengel, & Becher, 2010). Despite the (Mutch, Alberman, Hagberg, Kodama, & Perat, 1992). physical and communicative challenges, children with Augment Altern Commun Downloaded from informahealthcare.com by University of Toronto on 10/18/11 These motor impairments are reflected in the major- DCP tend to have relatively good cognitive skills (Jan, ity of children with DCP as significant impairments in Lynch, Heaven, & Matsuba, 2001). gross and fine motor skills. Himmelmann, Hagberg, This dilemma can be framed in the terminology of the Wiklund, Eek, & Uvebrant, (2007) found that 79% International Classification of Functioning, Disability (38/48) of their sample of children with DCP were clas- and Health (ICF): A child’s cognitive capability exceeds sified as a level IV or V on the Gross Motor Function his or her cognitive performance and this can have a Classification System (GMFCS), suggesting limitations tremendous impact on both the child’s and the fam- in self-mobility while 77% (37/48) were classified as a ily’s quality of life, specifically with respect to the basic level IV or V on the Bimanual Fine Motor Function communication of an individual’s preference (Craig, (BFMF), indicating that fine motor skills were at best Tran, McIsaac, & Boord, 2005; WHO, 2001). One way limited to grasping (Himmelmann, Beckung, Hagberg, to narrow this gap is to introduce technology as an envi- & Uvebrant, 2006). ronmental facilitator. *Correspondence: Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Rd, Toronto, ON M4G 1R8, Canada. Tel.: +1 416 425 6220 ext. 3515. Fax: +1 416 425 1634. E-mail: [email protected] 150 Detecting Communicative Intent in HKM 151 Access Technologies for Children with This insight about the client’s communicative intent is Hyperkinetic Movement regarded as indispensable and thus the caregiver often acts as the liaison between clinicians and the individual Despite reports that arm trajectories are more var- with profound disabilities (Hemsley, Balandin, & Togher, ied in children with DCP compared to children with 2008; Yamasato et al., 2007). On the other hand, clini- typical development (Sanger, 2006), automatic ges- cians can provide a fresh and unbiased opinion about a ture recognition may be a potential access technology client’s communication. In fact, Petry & Maes (2006) for children with excessive movement. Roy, Panayi, argue that both caregiver and clinician interpretations Erenshteyn, Foulds, and Fawcus (1994) used drama should be considered as complementary viewpoints. to elicit gestures in children with cerebral palsy; in this However, undue stress is placed on the caregiver or cli- study, four children were able to make 12 to 27 rec- nician who serves as the patient’s exclusive translator, ognizable gestures based on arm position, velocity, and and interpretation errors may abound (Happ, Roesch, acceleration signal features. Building on these findings, & Kagan, 2004). Studies have reported that system- Morrison and McKenna (2002) utilized a computer atic assessment of a patient’s preference, for example, vision-based gesture recognition system for a child with by counting “approach responses” (Pace, Ivancic, cerebral palsy with only a 5.6% error rate. Similar stud- Edwards, Iwata, & Page, 1985), more accurately reflects ies have been successful at utilizing gesture recognition a patient’s choice than mere clinician belief, furthering to track nose, chin, thumb, or foot movement (Betke, the notion that clinician opinion should not be the sole Gips, & Fleming, 2002; Glips, Betke, & DiMattia, interpretation of patient preference (Green, Gardner, & 2001). Collectively, these studies indicate that, even Reid, 1997; Reid, DiCarlo, Schepis, Hawkins, & Strick- with increased variability in HKM, children may still lin, 2003). be able to produce machine-discernible patterns. How- In light of the above, an integrated approach that ever, no studies have directly examined the possibility embodies multiple methods and perspectives may be a that HKM may carry useful information relating to an promising strategy for detecting preference in HKM. In individual’s preference. particular, in this paper, we propose to systematically analyze a time-varying quantitative measure of upper Rationale for an Integrated Approach to Preference body movement alongside an observational description Detection Amid HKM of this movement, incorporating viewpoints of both the To address the hypothesis of preference-related con- primary caregiver and clinician. tent in HKM, a systematic description of movement is required. Movement is routinely quantified through calculating the change in velocity over time, or the Methods For personal use only. acceleration of the movement; this is captured using An Integrated Approach to Decode Preference in HKM accelerometers (Shaikh et al., 2008). Movement is also characterized through real-time and retrospective The integrated approach contains three main com- observational techniques. One such technique is Laban ponents: a communication activity, observational Movement Analysis, a descriptive tool that qualitatively movement analysis, and automatic movement classifi- assesses movement with respect to four major compo- cation. Figure 1 provides an overview of this process nents: body, effort, shape, and space (Swaminathan and each component is described in more detail in the et al., 2009; for a complete review of Laban Movement sections that follow. The top portion of the figure is Analysis please refer to Newlove & Dalby, 2004). How- the communication activity, which provides the con- ever, the combination of quantitative and observational text for video and biomechanical data collection. The analysis is less common, although the idea of “meth- left half of Figure 1, observational analysis, assesses Augment Altern Commun Downloaded from informahealthcare.com by University of Toronto on 10/18/11 odological pluralism,” or combining multiple methods, clinician and caregiver ability to visually discern move- is strongly advocated in the communications literature ments associated with different preferences. The right (Petry & Maes, 2006; Reid & Green, 2002). This idea portion of Figure 1 outlines the automatic movement is relevant to the problem of decoding preference via classification, which gauges the ability to algorithmi- movements, in that quantitative data may enhance the cally discriminate between preferences on the basis of detection of communicative intent, while observational biomechanical time series. analysis may provide valuable contextual information