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

Abstract

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.

Scanning-Based Interaction Techniques for Motor Impaired Users

“…The usage of an ambiguous keyboard layout, including more than one letter in each key, such as for example in mobile phones, was proposed by (Miró-Borrás & Bernabeu-Soler, 2009). In their keyboard, the typical scan matrix is replaced by a smaller one with only three cells, having the characters arranged in alphabetical order.…”

Evaluation of an Ambiguous-Keyboard Prototype Scanning-System with Word and Character Disambiguation

“…Ambiguous keyboards may be implemented with physical buttons (physical keyboards) but also on screens (virtual keyboards). In this case, keys can be accessed by pressing directly the screen or by using one or more switches as input devices and a scanning technique that moves the cursor among the keys [17]. This technique allows users with motor disabilities to enter text into a computer.…”

“…All of the preceding proposals use disambiguation algorithms based on word prediction or word completion. In [18] we presented a two-key keyboard with CLDM, and in [17], we expanded it introducing WLDM, using a three-key alphabetically ordered keyboard. WLDM is an adaptation from the method "one key with disambiguation" from mobile phones and the disambiguation is done after selecting all the necessary cells to enter a word.…”

“…This research proposes a novel alternative to assigning letters to keys called CGA (Character Graphical Association), where letters with similar graphical characteristics are grouped into the same key, leading to families of four, three and two-key simple and easy-to-learn keyboards. All CGA layouts were analyzed when assigned to a text entry system based on scanning with the two disambiguation algorithms described in [17]: Word Level Disambiguation Mode (WLDM) and Character Level Disambiguation Mode (CLDM). The scanning system uses only one switch as input device.…”

“…In the following section we propose the CGA specifications. Then, we quickly review the methodology for analyzing scanning systems with ambiguous keyboards, specifically those working with WLDM and CLDM [17], [18]. We also present an empirical evaluation of a scanning system with layout CGA3-122 and both DM.…”