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Abstract

For people with functional impairments, independent control of a computer is often an important part of everyday life. However, in order to be of benefit, computer systems must be accessible. For people with motion-impairments, the keyboard, mouse and monitor arrangement can be difficult, if not impossible, to use. Symptoms such as tremor, spasm, restricted range of motion, and reduced strength can often restrict the extent to which a keyboard and mouse are useful.

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... Existing works in accessible computing mainly point out the problems faced by disabled people in pointing or typing (Hwang, Langdon, Keates, Clarkson, & Robinson, 2002;Keates, Trewin, & Paradise, 2005;Trewin & Pain, 1999), but there is not much reported work on quantitative analysis of effect of different impairments on pointing performance. Previous works are mainly based on description of diseases or self-report on the level of disability (Gajos et al., 2007;Hwang et al., 2002;Trewin & Pain, 1999). ...
... Existing works in accessible computing mainly point out the problems faced by disabled people in pointing or typing (Hwang, Langdon, Keates, Clarkson, & Robinson, 2002;Keates, Trewin, & Paradise, 2005;Trewin & Pain, 1999), but there is not much reported work on quantitative analysis of effect of different impairments on pointing performance. Previous works are mainly based on description of diseases or self-report on the level of disability (Gajos et al., 2007;Hwang et al., 2002;Trewin & Pain, 1999). A few researchers looked at the reaction time of users (e.g., Single Switch Performance Test [2011]) system or papers by Keates, Clarkson, and Robinson (2000), but there is not much reported work on objective evaluation of human factors and then relating them with human-computer interaction parameters. ...
... This fact should be considered when designing accessible keyboards or remote controls. Developing adaptation algorithms like gravity well (Hwang et al., 2002) may be a promising approach for making the touch screen usable for more users and thus further reducing the pointing time. ...
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... However, if the user aims to click at the edge of the button, as in the case of the rightmost button labeled "Disconnect," the user may end up clicking on a neighboring button-in this case the right arrow key (marked with dotted red circle). We can alleviate this problem by employing an adaptation principle called gravity well (Hwang, Langdon, Keates, Clarkson, & Robinson, 2002). The gravity well will attract the pointer in the middle of a button, if it is in vicinity of the button. ...
... The thick blue line in Figure 40 shows the modified cursor traces after employing the gravity well, and the dotted red circle highlights how the cursor has been attracted to the middle of the Disconnect button influenced by the gravity well. Similar analysis can also be done for other adaptation algorithms like cursor path averaging, damping (Hwang et al., 2002), and setting parameters for those algorithms. In fact, we have already used the simulator to design and evaluate accessible interfaces and interaction techniques (Biswas, 2010). ...
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... The prediction works in the following way If a user has tremor in hand or less than 10 Kg Grip Strength The predicted adaptation will be Gravity Well and Exponential Average Else The predicted adaptation will be Damping and Exponential Average In the first case, the adaptation will remove jitters in movement through exponential average and then attract the pointer towards a target when it is near by using the gravity well mechanism. Details about the gravity well algorithm can be found in a different paper [3] [10] ...
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... This model works based on a rule based system and does not address the basic perceptual, cognitive and motor behavior of users and so it is hard to generalize to other applications. Apart from full scale systems, there are also a few approaches which tried to adapt pointing devices like Gravity Well [12], SteadyClicks [29] and adapting pointing [15] by changing control-display ratio of a gesture based system. ...
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... Such a measure reveals differences in cursor behaviour that can be used to discriminate individuals or impairment type. Other measures under test include: distance travelled for a range of cursor speeds; and distance travelled for a range of radii from target (Hwang, Langdon, Keates, Clarkson, and Robinson, 2002). ...
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Chapter
Movement plays an integral role in human-computer interaction. In particular, mouse movements can occupy as much as 65% of the time spent interacting with a graphical user interface (Johnsonet al 1993). However, for users with impaired motion, symptoms such as tremor, spasm, and co-ordination difficulties can make it often difficult, and sometimes impossible, to perform the movements required to control a mouse accurately (Trewin and Pain, 1999).
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Purpose The purpose of this paper is to design an adaptation algorithm to facilitate pointing in electronic interfaces by users with motor impairment. Design/methodology/approach First, the algorithm was optimized using a simulator, then the algorithm was validated through a user study involving seven motor‐impaired and six able‐bodied users and three different pointing devices. Findings The algorithm significantly reduces pointing time overall and most participants pointed quicker with the gravity well than without it. Originality/value The adaptation algorithm can significantly reduce pointing time for both motor and situational impairment.
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