Improving the Usability of a Mainstream Cell Phone for Individuals with Low Vision

Abstract

This study investigated improving the usability of a mainstream cell phone for use by individuals with low vision by providing a means to display the text of the keys in large print on the phone's screen. No functionality was removed and no special equipment was required, and thus access was provided at no extra cost, which is a different paradigm from other forms of assistive technology, which usually require individuals with disabilities to purchase special models or external adaptation to use available models. The enlargment techniques we tested were designed to be transparent and accessible by users whenever they need extra assistance in dialing. This study was based on the hypothesis that the accuracy of dialing mainstream cell phones by people with low vision would improve with the provision of enlarging techniques. The enlargement techniques were expected to be of greater assistance when users with low vision were dialing telephone numbers with letters rather than when dialing digit-only number sequences. METHOD Instrument The commercially available Kyocera 7135 smartphone (a cell phone plus personal digital assistant) was chosen for the study because of its programmability. Although the cell phone was turned off during the dialing tasks, the tones associated with key presses were reproduced to simulate the typical experience of using the cell phone. The cell phone used in this study is pictured in Figures 1 and 2. [FIGURES 1-2 OMITTED] The Kyocera 7135 is a flip cell phone with a color screen and a 7/8-inch by 1 7/8-inch Graffiti touch panel at the base of the screen. A white label with a blue diamond (BD) was placed over this touch area to create a single button, the BD-button. Because of the lack of contrast between the background and the numbers and letters on the phone's keys, white labels with black text containing each key's information were placed over the keys. Enlarging techniques Two enlarging techniques (suspend and display and delay and display) were developed, and the programs were loaded into the cell phone. The two techniques used the same degree of enlargement on the cell phone's screen. Both were designed to function with the BD-button that was described in the Instrument section. The techniques differed in the way that a number is entered into the cell phone after a key is pressed. The suspend-and-display technique suspends operation of the dialing function and displays, without dialing, the enlarged key labels. When using this feature, the caller holds down the BD-button and presses another key. The number and letters associated with that key are then enlarged and displayed on the screen (but the key is not dialed or activated). When the caller finds the key that he or she wants to include in the number or letter sequence to be dialed, he or she releases the BD-button and pushes the desired key again to input the number or letter of the key (see Figure 1). The delay-and-display technique involves a time delay for activation of a depressed key (Vanderheiden, Law, & Kelso, 1999), in which the user again holds down the BD-button, and the selected key is again enlarged and displayed. However, with the delay-and-display mode, the number is entered into the dialing queue only when the key is held down for a prescribed period of time (the duration of the dialing delay can be adjusted according to user preference). A progress bar at the top of the screen indicates the length of time before the number will enter the dialing queue (see Figure 2). Both the suspend-and-display and the delay-and-display techniques work for all keys on the cell phone. For both techniques, when the BD-button is released, the cell phone returns to standard operation. Experimental design The experiment was divided into four stages. In each stage, the participants used a different dialing mode: 1. …