that failure to complete the associated
task would have dire consequences. This
follows the logic that if you do something
out of self-preservation, then you believe
that you would be harmed in some way
if you failed to do the task. This criterion
helps establish that the task is associated
with a scenario of sufficient gravity to
compel vigilance.
Using these criteria, a small pilot
study was performed within which two
user groups were recruited and their
device usage monitored for vigilance.
One user group contained situated
users and the other group contained
mobile users. Eight participants were
selected for each group— 16 in total.
Participants were asked to maintain
an online daily journal, where they
described a specific session of use that
occurred on that day. Over the course
of two weeks, each participant logged
14 unique journal entries. A total of 224
journal entries were recorded.
Users were not directly asked if
they were being vigilant or not. Rather,
they provided details about their
usage sessions: what they were doing,
the importance of these tasks, what
prompted their usage session, and if
failure to perform the tasks would have
created any problems. A specific subset
of the responses was associated with
the vigilance criteria. If a participant’s
journal entry on any particular day
contained all of the responses that
mapped into the vigilance criteria,
then that session of use was flagged as a
vigilant one.
For the mobile group, 43. 8 percent of
the recorded sessions were vigilant. For
the situated group, 14. 3 percent of the
recorded sessions were vigilant. Thus,
mobile users were about three times
more likely to be vigilant than situated
users (Figure 3).
Mobile users had a higher standard
deviation of 2. 6 vigilant sessions per
user compared with 1. 5 for the situated
users, indicating greater variance in the
vigilance of mobile users. This could
be because mobile devices support a
greater diversity of usage scenarios,
whereas situated usage was more
often correlated with planned work.
There may also be more variation
among mobile users in the perceived
importance of monitoring the device.
For a portion of the study, users were
also directly asked if they felt a need to
be watchful over their devices each day.
On 78 percent of the days observed,
mobile users said yes, compared with 44
percent for situated users. The ratio of
daily watchfulness to vigilant sessions
was 1.8: 1 for mobile users, and 3: 1 for
situated users. As a measure of quality
control for the study, vigilant sessions
1. Vigilant Sessions
The percentage of documented
sessions that matched the
vigilance criteria.
2. Watchful Days
Percentage of days that users
felt the need to be watchful.
MOBILE 43.8%
14.3%
78%
SITUATED
COHORT VIGILANT SESSIONS
VIGILANCE – CORRELATION TO WATCHFULNESS
WATCHFUL
DAYS
44%
25 (78%)
14 (44%)
15
6
15
5
100%
83%
32 days
Vigilant sessions on
days where users
noted watchfulness
Vigilant sessions on
days where users felt
need to be watchful
Correlation of
vigilant sessions
and watchful days
112 sessions
MOBILE
SITUATED
48 ( 43.8%)
16 ( 14.3%)
MOBILE
SITUATED
Figure 3. Daily journal analysis.