Keyboard Map

As stated in Chapter 1, my primary concern in this research is the design of the auditory display output, and the functions used to control and explore it. How the commands map to a physical input device is a secondary concern, and only of importance since it is a requirement for evaluating the display with users. To produce a simple, familiar, easy to learn implementation for evaluation, I decided to map the Clique commands to

Table 5.8 lists all of the Clique commands along with the keys that trigger them. Figure 5.6 shows the spatial layout of the Clique keyboard map. The user activates most of the commands by simply pressing the required keys. Other keys must be prefixed with a modifier key. Note that the majority of the command keys are located on the numeric keypad. Also note that the left, right, up, and down arrow keys may be used in place of Keypad 4, 6, 9, and 2.

Figure 5.6: Clique keyboard map. The inset shows command keys available while Key- pad 0 is held.

Quasimodal Keys

To implement all of the Clique commands on a keyboard, some of the keys must serve more than one function. For example, the system must distinguish use of the character keys for text editing from use of the characters for entering search queries. This problem could be solved by introducing explicit modes into the interaction with a subtask. Clique could, for instance, require the user to visit the task menu, select aSearch this text task (i.e., the search mode), enter search terms in that task, complete the task, and then return to his or her initial task (i.e., the original mode) in order to hear the first search match. Thereafter, additional shortcut keys could allow the user to navigate to the previous and next match while returning to the Search this text task could allow the user to modify the search.

The design of Clique could certainly support this modal solution, but it is less than ideal. The addition of modes in each subtask or new tasks representing the modes requires that the user switch contexts each time he or she needs to invoke the command. Even with persistent reminders and announcements when changing modes, the mode

places an extra memory burden on the user and slows down interaction. The user must check what mode he or she is in by listening to the environmental sounds, and Clique must take some time to announce a mode change. On the other hand, if such reminders and announcements are eliminated in the interest of speed, then the user must recall the active mode from memory alone.

To avoid these problems, Clique supports the concept of quasimodal commands. A user activates a quasimode by pressing and holding a key and leaves the mode by releasing it. The tactile and proprioceptive sensation of pressing a key serves as an effective reminder of a special mode over an extended period of time (Raskin, 2000). GUI keyboard accelerators (e.g.,Alt-F to access the File menu) are primitive implementations of quasimodal commands. The user must press Alt before pressing F to trigger the opening of the file menu instead of the insertion of the letter F in text. Capitalization of text by holding Shift represents a true quasimode. Holding Shift while pressing one or more alphabetic keys produces multiple capitalized letters.

Clique has three quasimodes. First, pressing and holding either of the two Alt keys puts Clique into the searching quasimode by issuing the Start searching command. While Alt is held, all character key presses append to the keyword search string (Add character to search). Pressing Backspace while holding Alt removes the last character in the search (Remove character from search). Using the left and right arrow keys while holding Alt skips to the previous and next match for the entered text using the Go to previous search match and Go to next search match commands. Releasing the Alt key issues theStop searching command, leaving the last announced match as the active item. Second, pressing and holding the Keypad +key puts Clique into recording mode by giving the Start recording command. While the user holds this key, Clique marks all text spoken by the content assistant for later recall in the memory menu. When the user releases this key, he or she issues the Stop recording command and Clique stops remembering text. The use of this key does not interrupt output from other commands,

nor does it preclude the user from giving other commands while recording. For instance, the user may visit the program menu, hold the recording key, press right arrow three times, and then release the recording key. This operation will cause Clique to place the three program names announced into one chunk in the memory menu.

Third, pressing and holding the Keypad 0 key puts Clique into system mode. Press- ing keys on the numeric keypad with zero held results in the execution of system com- mands like Increase volume and Decrease rate. Compared to the search and memory modes, the system mode is simpler and more reminiscent of basic accelerator keys in GUIs.

To support quasimodes using these keys, Clique must prevent certain keystrokes from reaching the underlying GUI applications. Section 5.3.1 describes this Clique function.