V. PERFORMANCE OF THE SMART PHONE VIBRATION
WATCH
We verified whether users could recognize the time by our
vibration watch using smart phone. We used five times (21:18,
05:49, 19:11, 12:53 and 08:24) for the experiment. These times
consist of numbers which participants can recognize easily or
not. The participants felt the vibration corresponding to the
hour or the minute, and answered the number corresponding to
it orally. This experiment is the same as was performed earlier
using a mobile phone [2]. From the result of the experiment of
some exhibition we thought that there was no difference in the
recognition rate of visually impaired people and non-disabled
people. So, for the present experiment, we chose the nondisabled
people who participated in the previous experiment in
order to provide a more direct comparison of a mobile phone
and a smart phone.
The procedure was as follows: An examiner sets a time of
the smart phone and hands it to a participant. The participant
flicks their finger on the screen toward left or right and
then orally answers the number corresponding to the hour
or minute. Each participant was prompted at least twice for
each number. If their first answer was different from the
second answer, the participant was prompted to answer a
third time. We defined success as two consecutive correct
answers or two correct answers out of three answers. In a preexperiment
practice session, participants were prompted with
vibrations corresponding to 16:08. We selected 16:08 because
these numbers can be recognized easily and the vibration of
these numbers includes both short and long vibrations. Each
participant was tested five times. TABLE II shows the results.
Nine participants were each prompted with two vibration
sequences — hour and minute — for each of the five test times.
Therefore, the total number of tests was 90. Participants made
only four errors, thus achieving a success rate of 86/90=95.5%.
The errors are shown Table III. The errors include feeling
a long vibration as a short vibration or mistaking four short