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The Effect of Interruption Modality on Primary Task Resumption

Raj M. Ratwani1,2, Alyssa E. Andrews2, Jenny D. Sousk2, J. Gregory Trafton1
Naval Research Laboratory1, George Mason University2

The majority of empirical papers investigating the effect of interruption modality on primary task
resumption have been grounded in Multiple Resource theory; this theory stresses the benefits of cross-
modal information presentation. Alternatively, Altmann and Trafton’s (2002) Memory for Goals
theory suggests that maintaining an association between the suspended primary task goal and relevant
environmental cues is critical to the task resumption process. Using reaction time and eye movement
measures, the theoretical predictions of these two frameworks were empirically examined to
determine whether interruption modality influences primary task resumption.

INTRODUCTION

Attempting to complete a task in a busy office setting is
nearly impossible without being interrupted. The sources of
interruptions in work settings are abundant; interruptions
can take the form of phone calls, emails, instant messages
or a colleague stopping by your office, just to name a few
possibilities. In fact, Mark and Gonzalez (2004) have
suggested that workers are only able to spend an average of
eleven and a half minutes in continuous work before being
interrupted.
The majority of the literature investigating the impact of
interruptions on primary task performance has shown that
interruptions are generally disruptive (Adamcyzk & Bailey,
2004; Hodgetts & Jones 2006a,b; Monk, Boehm-Davis &
Trafton, 2004). However, interruptions often occur in
different modalities. For example, while working at a
computer one might receive a phone call (auditory
interruption) or one might receive an urgent email (visual
interruption). How does the modality of an interruption
impact the resumption process? Is one modality less
disruptive than another?
Altmann and Trafton’s (2002, 2007) Memory for Goals
framework is a prominent activation based theory that has
been applied to the interruptions paradigm (Hodgetts &
Jones 2006a,b; Monk, et al, 2004). This theory suggests
that the current most active goal directs behavior and the
activation levels of goals decay over time. When
interrupted, the current primary task goal is suspended and
the activation level of this goal decays. Upon resumption,
the time required to begin work on the primary task reflects
the process of retrieving the suspended goal. The higher the
activation level of the suspended goal, the more easily that
goal can be retrieved. There are several constraints in this
theory that determine the activation level of the suspended
goal. First, the strengthening constraint suggests the history
of the goal (i.e. frequency and recency of goal retrieval)
impacts goal activation. Second, the priming constraint
suggests that cues in the environmental context provide
associative activation or priming to the associated goal in
the primary task, and thus facilitate retrieval.
Although Memory for Goals does not make explicit
predictions about interruption modality and the resumption
process, the priming constraint can be leveraged to make
these predictions. Specifically, based on the priming
constraint, any interruption that allows for the associative
link between the environmental cues and the target goal to
be maintained should facilitate resumption. Thus, the
interruption modality that allows for this associative link to
be maintained will be less disruptive as compared to
modalities that do not allow for this associative link.
Alternatively, Multiple Resource theory (Wickens, 1984;
2002) makes a different prediction. Multiple Resource
theory would suggest that,all else being equal, cross modal
interruptions (e.g. auditory interruption- visual primary
task) will be less disruptive than interruptions that occur in
the same modality as the primary task (e.g. visual
interruption- visual primary task). There have been several
empirical papers grounded in Multiple Resource theory that
have investigated the effect of interruption modality (Ho,
Nikolic, & Sarter, 2001; Ho, Nikolic, Waters, & Sater,
2004; Latorella, 1998); these papers have resulted in mixed
support. Latorella found that there was no difference in
cross-modality conditions in terms of time cost. However,
when looking at error rates, there was some support for
Multiple Resource theory. Ho, et al. found that participants
sought to avoid interruptions that were intra-modal when
they were both visual; they took this to be support for
Multiple Resource Theory. Although there appears to be
some support for the benefits of cross-modal information
presentation, there is no direct evidence of a time cost
benefit within an interruptions paradigm.
The purpose of this study was to examine whether there
is a benefit to presenting an interruption in a different
modality than that of the primary task and to distinguish
between the Memory for Goals theory and Multiple
Resource theory in their accounts for the effect of
interruption modality. Specifically, we focus on resuming a
computer based visual primary task following either an
auditory or visual interruption. Given this focus, the

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Memory for Goals theory would suggest that the auditory
interruption would facilitate resumption to the degree that
the interruption will allow for the maintenance of the
environmental cues and the association to the suspended
primary task goal. Multiple Resource theory would make
the strong prediction that an auditory interruption would be
less disruptive to a visual primary task than a visual
interruption because of the cross modal benefit. An
experimental paradigm was designed to tease apart these
two theoretical predictions.
EXPERIMENT

In order to distinguish between the Memory for Goals
and Multiple Resource theories, two different interruption
modalities (auditory and visual) were manipulated across
three different conditions. In one condition an auditory
interruption was presented while the primary task interface
was still completely visible to the participant. In a second
condition, an auditory interruption was presented, but a
blank screen covered the primary task interface. In a third
condition, a visual interruption was presented which
completely occluded the primary task interface.
Given that the primary task is visual, Multiple Resource
theory would suggest that resumption of the primary task
following the visual interruption should be more difficult
than resumption following either of the auditory
conditions. The auditory interruptions leverage the benefits
of cross-modal information presentation, while the visual
interruption does not.
The Memory for Goals theory makes a slightly different
prediction. Memory for Goals would suggest that the
conditions in which participants can not explicitly maintain
the associative link between the cue and goal will result in
more difficult resumption as compared to the conditions in
which this link can be maintained. The only condition
where this link can be explicitly maintained is the auditory
condition with the primary task interface visible. Thus, this
auditory condition should result in faster resumption times
than the auditory condition with a blank screen and the
visual interruption condition. Further, since both the
auditory interruption condition with a blank screen and the
visual interruption condition do not allow for maintenance
of the associative link, these interruptions should be
equally disruptive.
In addition to collecting reaction time measures to
differentiate between these two theories, eye movement
data were collected as well. The eye movement data should
provide explicit evidence as to whether participants are
actually maintaining the relevant environmental cues as the
Memory for Goals theory would suggest.




Method

Participants. Forty-eight George Mason University
undergraduate students participated for course credit.
Materials. The primary task was a complex production
task based on Li et al (2006), called the sea vessel
production task (see Figure 1). The goal of the task was to
successfully fill orders for different types of navy sea
vessels. At the beginning of each trial, an order sheet for
two different types of navy sea vessels was presented in the
center of the screen (see Figure 1). To fill the order, the
participant had to specify information from this order in
five different modules on the computer interface; the
modules corresponded to the vessel name, material, paint
scheme, weapons and location of delivery. There was a
specific correct procedure for filling each order. After
entering information in each of these modules the order
was processed by clicking the process button and finally
the order was completed by clicking the complete contract
button.
The interrupting task consisted of 3 addition problems.
Each problem required the participant to take the sum of
two single digit addends ranging from 1-9. Each addition
problem was presented serially and participants were given
five seconds to answer each problem (this time included
presentation time); thus, the total interruption duration was
15 seconds. The addends were randomly generated. The
addition problems were either presented aurally or visually.
The time required to present each addition problem was
equal for all types of interruptions.


Figure 1. Screenshot of the primary task interface.

Design. Interruption modality was manipulated between
participants. Although there were two different modalities
(visual and aural), there were three interruption conditions:
auditory interruption with full view of the primary task,