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The application of Human Computer Interaction principles to Electronic Assistive Technology. Simon Judge MEng, MIET Clinical Scientist Access to Communication and Technology, Birmingham, UK. Contents. My role
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The application of Human Computer Interaction principles to Electronic Assistive Technology Simon Judge MEng, MIET Clinical Scientist Access to Communication and Technology, Birmingham, UK ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Contents • My role • The use of Human Computer Interaction (HCI) models for Electronic Assistive Technology (EAT) • Examine literature behind an EAT activity (switch access) • Introduce the Model Human Processor (MHP) as a potentially relevant model • Provide examples of applicability • Implications for Assistive Technology • Future suggested work/direction ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
My role • Clinical Scientist • Within specialist NHS Electronic Assistive Technology (EAT) team in the UK • Clinical role: wide range of client contact (any age, any condition) • Assess for and provide: • Communication aids • Environmental Control systems • Computer Access equipment • A unique insight into man-machine interaction and the use of AT devices ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Hypothesis • The evidence base for Electronic Assistive Technology (EAT) is small and immature • Technology and techniques used in other fields are not readily transferred to EAT products or practice • EAT provision is not necessarily based on evidence or theory • To develop the EAT evidence base, the field should use models and theories from other fields. ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Assistive Technology • Assistive Technology field is concerned with: “Assistive Technology (AT) is any product or service designed to enable independence for disabled and older people." King's Fund Consultation (14th March 2001) ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Electronic Assistive Technology • No clear definition of Electronic Assistive Technology (EAT). To derive a definition: “Electronic systems designed to enable independence for disabled and older people” ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Human Computer Interaction • The Human Computer Interaction (HCI) field is involved with: “Human Computer Interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use…” ACM SIGCHI ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
HCI - EAT • HCI should, thus, obviously be heavily involved with EAT? • Lets use switch access as an example… ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Input Bandwidth Switch Access 101 • Part of a spectrum/bandwidth of input • Using a single binary source to transmit information [ DEMO ] ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Switch Access • Within EAT switch access is an important method of access • Specialist services have a lot of contact with switch access. Generally single switch auto-scan is the default. Jones and Stuart (2004) 1 • At the moment switching is a ‘clinical black art’ • Even the literature is not based on evidence. Robbers and McDonald, Communication Matters (2005) ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Input Bandwidth Switch Access – Questions: • What is the most effective type of switch access for different people? • What are the pre-requisite skills required to scan • What is the cognitive load of different scanning techniques • How is input bandwidth laid out at the switch end? ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Switch Access Evidence • Comprehensive Literature Search • General search terms • Published and unpublished work: • 22 papers (!) of over 1000 searched • 17 published in peer-reviewed journals • ~1% of published work on Assistive Technology. • Few directly related to switch access • Few involved user trials (mostly case studies) • Equivalent (independent) work found similar results - few papers and lack of evidence in literature. Robbers and McDonald (2005) ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Models • Models allow a theory to be better understood: “By it’s nature a model is a simplification of reality. However, a model is useful if it helps in designing, evaluating, or otherwise providing a basis for understanding the behaviour of a complex artefact such as a computer system.” MacKenzie (2003) • Few, if any, models in Assistive Technology. • Models used extensively to evaluate HCI tasks • Model Human Processor is one such model ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Model Human Processor (MHP) • Three components: • Perception • Cognition • Motor • Principles for each component and rules which describe components and their interaction. Card, Newell & Moran (1983) ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Perception • MHP says: • Response time of perceptual processor is proportional to intensity of stimulus • Information is stored in memory according to the type of stimuli (e.g. acoustic, visual) • Information ‘decays’ from working memory and may be stored in long term memory • About 100msec • Measure by determining smallest perceivable event (e.g. moving image on film) Time to perceive an event e.g. perceive pattern of letter S ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Cognition Time to “connect inputs from the perceptual system to the right outputs of the motor system” e.g. pattern S is equal to letter S • MHP says: • Cognitive processor time decreases with practice (Power Law of Practice) • Cognitive processor time decreases with task load. • About 70msec • Measured by ‘matching’ tests ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Motor Time taken for ‘micro-movements’ to translate thought into patterns of voluntary movement e.g. hit key that has S on it • MHP says: • Time to move to a target depends on distance and size of target (Fitts Law) • About 70msec • Measured by repetitive motor tasks
MHP :: Principles Fitts Law • Predicts time to move hand to target given the distance and size of the target Tpos = IM log2(2*Distance/Size) • i.e: Time is longer the further the target is away and the smaller it is. • Fitts law shown to match use of mouse well • How about a user with motor impairments? ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Principles Hick-Hyman Law • Predicts the “choice reaction time” RT = a + b log2(number of choices) • i.e. The more choices the longer it takes to react. • The reaction time to a choice depends on it’s likelihood – the more likely the option, the quicker the reaction ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Principles Power Law of Practice • Predicts the effect of performing a practiced task. Tn = T1n- • i.e. Time decreases (exponentially) with practice ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP :: Example • TP – Perceptual Processor • Perceive the second symbol and store in working memory visual store • TC – Cognitive Processor • Tc * 1 Match symbol to previous (or not) • Tc * 2 Decide to press YES or NO • TM – Motor Processor • Process the signal to push the button • Total: Tp + 2TC + Tm User is shown a series of symbols – she has to press ‘YES’ when two identical symbols are shown in a row and ‘NO’ otherwise (I.e. a game of Snap!). ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP for Assistive Technology • Koester & Levine (1997): • Used a keystroke-level model to model word prediction tasks. • Keystroke level model is a Goals/Operators/Methods/Selection Rules (GOMS) model – similar to the MHP • Validated the model for use for this task • Successfully predicted prediction selection times • John P Hansen – other use of GOMS model. ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP for Assistive Technology • Keates, Clarkson and Robinson (1998) • Measured the perceptual/cognitive/motor times for range of able bodied and motor impaired users. • Slower times for motor-processor (~50%) • Slight variation in cognitive-processor • Completion of task (pressing key on stimulus) did not conform to the MHP for motor-impaired users. • Motor impaired users conformed to modified model with additional cognitive and perceptual processor cycles. • No further research indicated… ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
MHP and Switch Access • Applies to switching? • Many examples in Card et al. (1983) refer to response to stimuli and selection from lists • Some work and reference to MHP in Assistive Technology papers • No extensive uptake of the model or any other models noted • I propose that the investigation of the model with respect to switch access would provide valuable information. ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Health Warning! • I am not: • proposing models as a way of replacing common sense • suggesting that a model will give us all the answers about switching • saying that all users/clients will fit nicely into a set of categories • Each person is different and the environment and motivation is almost always the most important factor • However, I believe that using HCI models for switch access can provide valuable information and provide a basis for developing an evidence base… ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Modelling Examples Switched Joystick VS P&G Mouse • What is quicker? Using 3/4/5 switches as a directional joystick or a Joystick Mouse (e.g. P&G Joystick) • Some (AAC) devices are removing ability to use more than 2 switches. The recommended replacement is to use a mouse device. • Is this better or worse? ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Modelling Examples AutoScan VS Inverse Scan • Anecdotally, most people use 1 switch AutoScan – why? • Inverse Scan is being dropped by AT products as an option • Is the cognitive load of AutoScan more or less that UserScan? ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Research Areas • Pre-requisit skills for switching • Validate the MHP for different switching tasks • Evaluate the cognitive loads of different components and methods of switching • Monitor the effect of different methods of teaching on learning switching skills • Investigate expert switch/device use • Effects of different conditions on the components of the model • ……… ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Conclusions • Used MHP as an example of a model that could be used with switch access • EAT could build on the HCI field and apply a number of relevant models and theories • Aim is to optimise switch access for users to enable them to be as effective as possible. ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
Other Relevant Work • “Switch Access to Technology, a comprehensive Guide”. (Standards and reference manual for switch access) D Colven & S Judge, released shortly. • Development of evidence base on Assistive Technology: www.assistech.org.uk • Open Source software for Assistive Technology: www.oatsoft.org ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
References • Citations: www.citeulike.org/user/simonjudge/ tag/switching • Main HCI reference: Human Computer Interface; Card, Newell & Moran (1983) • Main AT-HCI reference: Use of Model Human Processor for people with motor impairments; Keates, Clarkson and Robinson (1998) ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology
www.SJinterface.co.uk Simon.judge@sbpct.nhs.uk ICCHP 2006 – Young Researchers – Simon Judge The application of Human Computer Interaction principles to Assistive Technology