NOVEMBER–DECEMBER 2014 INTERACTIONS 63 INTERACTIONS.ACM.ORG
were expected to correlate to days when
the user described a need to be watchful.
This was found to be true: 95.5 percent
of the vigilant sessions occurred on
watchful days. The prevalence of
watchfulness may also suggest that
vigilant behavior occurred outside the
sessions detailed in journal entries.
As an initial pilot, this study had
several limitations, including a small
sample of 16 individuals. Additional
studies should be performed with
a larger sample to substantiate the
findings, ideally considering age and
other demographics. This research also
relied upon self-reporting rather than
instrumentation or direct observation.
The application of more quantitative
methodologies could help mitigate
participant bias, subjectivity, and errors.
Still, these early findings
are compelling. A new form of
vigilance has likely emerged in our
evolving technological landscape.
This new vigilance invokes and
spans intermittent sessions of use,
predominantly on mobile devices.
Almost 50 percent of self-reported
mobile sessions captured in this pilot
were vigilant in nature, suggesting that
vigilance is extremely prevalent among
everyday mobile users.
So why does this matter? First, because
any product or service that is designed
for and delivered to mobile devices
is being inserted into a usage session
that just as likely as not was invoked
by vigilant behavior. How should
interactions be designed to integrate into
that? Second, for any product or service
that is designed for mobile use, we must
consider whether it will directly compel
vigilant usage. In either case, vigilance
is an important dimension of how we
must think about designing for mobile.
Consider these interaction design
principles for supporting vigilance:
• Vigilance first. Vigilance compelled
the user to start their task. As such, the
initial interface should be optimized for
vigilant use. Users should be presented
only enough information to know if they
need to take further action or not. All
actions should be enabled via efficient,
intuitive paths within the application
flow. The interface should eliminate
• Disengagement. Alerts should be
minimized and vigilance should be
supported via the shortest possible
session of use. When the vigilant
task is completed, the session should
terminate. Shorter sessions create
less interruption and distraction from
the real-world experiences the user is
• Habituation. Interactions should
be standardized and not novel. Users
should be able to easily form habitual
usage patterns that require less cognitive
focus to perform. This also means
that users may become desensitized to
signals and alerts over time—variance
can be introduced to combat that.
Vigilance likely isn’t the only
scenario that everyday consumer
experiences must support. Vigilance
emerges after a product or service is
used enough that the user begins to feel
the need to be watchful. Outside any
moment of vigilance, the user may be
more casual and exploratory, or even
immersed or deeply engaged.
These principles call for reductive
measures to better support vigilance,
yielding products that pack all of their
value into a delivery that’s overall
less engaging. Yet most consumer
applications are designed in an effort
to deepen user engagement. Vigilance
requires a paradigm shift. If you are an
interaction design practitioner, then
sooner or later these principles will
conflict with the business objectives
of your employer. Designers learn to
value the attributes of an engaging
user experience—immersion, focused
attention, and lengthy usage sessions—
often above all others, because user
attention is extremely valuable to
software companies. Online user
sessions are often monetized with
advertisements, and the more time
users spend within the product, the
more opportunities there are to display
ads. Many organizations track the
length of user sessions or the average
number of user interactions in order
to raise the amount of money they can
charge for ad impressions. Sites with
engaged users can charge more than
sites with disengaged users.
Even if your product doesn’t compel
vigilant use itself, there are many
other mobile products that already do.
Thus, even if you are only leveraging
mobile devices as a channel to engage
your customers, you should assess
and model interruptions and user
distractedness. Vigilance is still a
behavior you must consider.
In spite of all challenges, it is
important to design for vigilance in a
world full of mobile users. A decade
ago, before the proliferation of mobile
connectedness, it was safe for an
interaction designer to assume that
vigilant watchfulness was limited to
specific situated tasks performed by
trained professionals or operators,
and that the strain and distraction
of sustained vigilance was confined
to a user, in a chair, at a terminal. In
today’s world, that is an irresponsible
assumption for a designer to make.
1. Parasuraman, R. Sustained attention: A
multifactorial approach. In Attention and
performance XI. M. Posner and O. Marin,
eds. Lawrence Erlbaum, Hillsdale, NJ,
2. Mackworth, N.H. The breakdown of
vigilance during prolonged visual search.
Quarterly Journal of Experimental
Psychology 1 (1948), 6–21.
3. Parasuraman, R. and Caggiano, G. Neural
and genetic assays of mental workload. In
Quantifying Human Information Processing.
D. McBride and D. Schmorrow, eds.
Rowman and Littlefield, Lanham, MD,
4. Edmunds, M. Defense In Animals: A
Survey of Anti-predator Defenses. Longman,
New York, 1974.
5. Phillips, M.G. Designing for vigilance
during intermittent use. Proc. of the 4th
Annual ACM Web Science Conference.
ACM, New York, 2012, 243–246.
6. Turkle, S. Alone Together: Why We Expect
More from Technology and Less from Each
Other. Basic Books, New York, 2011.
7. Boyd, D. Why youth (heart) social network
sites: The role of networked publics
in teenage social life. In MacArthur
Foundation Series on Digital Learning
—Youth, Identity, and Digital Media
Volume. D. Buckingham, ed. MI T Press,
Cambridge, MA, 2007, 119–142.
M. Giles Phillips is a designer and
researcher examining the intersection of
physical and mediated experience. He is the
founder and executive director of Subforum, a
research and design institute, and serves as
the chief product designer at Constant Contact,
where he is responsible for Web and mobile
DOI: 10.1145/2670738 COP YRIGHT HELD BY AUTHOR. PUBLICATION RIGHTS LICENSED TO ACM. $15.00