T18: an ambiguous keyboard layout for smartwatches

We present a new ambiguous keyboard layout for smartwatches named T18. As the name implies, it is composed of 18 keys, and for this reason a key may correspond to more than one character. In those cases, the system chooses one of the characters based on a dictionary. The T18 keyboard layout is inspired by T9, with the main differences being that T18 has a greater number of keys and they are arranged in a QWERTY layout. The method was compared to OptimalT9, an improvement of the original T9 for smartwatches. The experiment showed a 39% advantage in text entry speed in favor of T18. In particular, participants typed at 15.7 wpm with T18 and at 11.3 wpm with Optimal-T9.