Text Entry in the E-Commerce Age: Two Proposals for the Severely Handicapped

Article excerpt


People with severe motor disabilities have extreme access difficulties with all kinds of web services especially when they want not only to surf the web, but also write some text, e.g., to participate in an e-activity. Several problems arise when using traditional scanning systems, such as the low text entry rate, the time consuming task of learning the scan matrix layout, or simply, the poor visibility of the web page due to the large surface needed to display the complete scan matrix on the screen. We propose a reduced virtual keyboard based on scanning with only one switch as input device. The scan matrix consists of only three cells, so ambiguity is present due to the assignment of 26 characters to the three keys. Word-level and character-level disambiguation modes are explored using a mathematical model, and the text entry rates for an expert user were 15.9 and 10.3 words per minute respectively, using a scan period of 0.5 seconds. This keyboard could be embedded into a web page using a Java applet, JavaScript code or a Flash application, or be programmed as an independent application.

Key words: Handicapped, Text Entry, Scanning, Disambiguation, Ambiguous Keyboard, ECommerce

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1 Introduction

The World Wide Web in general and e-commerce in particular play an important role in contemporary society. Nevertheless there are special groups of people who cannot take advantage of the recent technological advances, creating greater social differences between them and able bodied society. This is what is known as the digital divide. Following the publication of the web content accessibility guidelines (WCAG) release 1.0 by the World Wide Web Consortium in 1999 [4], there is a growing recognition that users with disabilities have the same rights as others to access Information Technology with opportunities and risks [1]. According to World Bank estimates, 10% of the world's population (over 600 million) suffers from some kind of disability [30], [20]. Taking into consideration this figure, two main points of view arise: social and economic. The first refers to the inclusion rights of everybody; the second refers to the potential business that the disabled represent.

The WCAG help disabled people to access the web. Nevertheless not all groups have the same opportunities. These guidelines help the group of severely handicapped people, especially those with severe motor disabilities, to navigate through the web pages of the site, for example, permitting them to jump from one hyperlink to another simply by pressing the "tab" key in a standard keyboard, but, what can users do if they cannot use a keyboard?. How can they enter text to participate in what is called e-democracy, for example to express their opinion on a particular blog, wiki or mailing list? People with motor disabilities use a wide variety of creative solutions to control both their environment and computers. In general, a motor disabled person does not have the ability to efficiently use a multidimensional input device such as a keyboard, a joystick or a mouse. Users with a severe motor disability such as quadriplegia have the capacity to produce "single bit" signals [37], [29].

Communication aids are devices developed or specially adapted for people with severe communication impairments. There is a wide variety of communication aids because these people have a large variety of skills, needs, and problems. Some people with severe motor disabilities can use their hands; others cannot, and have to use alternatives, such as mouth-sticks, head-sticks, switches, or eye-pointing devices. In general, most communication aids for people with severe motor disabilities are designed to work with or to emulate a keyboard. Switches can be operated using their head, hands, arms, knees, feet, legs, shoulders or any body part over which they have muscular control. Other kinds of switches work by detecting movement such as a tilting arm or head, making a sound or breaking a beam of light. …