Each test consisted of three sets of fifteen button selections. The first 5 selections of each set were discarded as practice runs. Figure 2 shows Subject 1 and Subject 2's mean selection time with both devices in each of the two tests. As can be seen, on average, the tongue device performed much poorer than the finger device in the beginning, probably due the fact that the tongue is not naturally used as an pointing organ. However, these early results demonstrate that an isometric tongue pointing device is a promising alternative to hand input devices.
More systematic experimentation is planned, pending further design improvements.
The current isometric pointing device implemented in the Tonguepoint had a transfer function that was optimized for the finger, but not for the tongue. This was intentionally done so as to be able to compare the tongue and finger with as little change of other design dimensions as possible. It is hypothesized that the performance of the Tonguepoint could be further improved if the transfer function were optimized for the tongue muscles. We thank Ted Selker for supporting the current work and building the framework under which this study was undertaken. Kim May implemented the electronic hardware used in the prototypes.