Last week’s post focused on vigilance decrement and its
effects on performance in vigilance tasks.
This week, however, we will focus more on understanding why this decrement
occurs in vigilance tasks by comparing the theories currently debated.
[1]Ever
stop to realize that you have just re-read the same sentence over and over but yet
have no idea what it said?
[2]Ever
start walking across a street not because you saw the walk signal but because
everyone around you began walking?
Ever realize that you have been sitting, blank and mentally
not present, only after being aroused by a teacher calling your name to answer
a question? [3]
If none of these, or anything similar have happened to you
then kudos, though you may not be human.
Cheyne,
Solman, Carriere, and Smilek (2009) explain
these everyday events as discrete mind-wandering states can be used to independently
contribute to performance failures in a variety of tasks. In State 1, resources are allocated to the
occurrent and dynamic task features.
Inattention in this state, such as re-reading a sentence multiple times
to discern its meaning during a reading task, is brief and unstable, resulting
in the waning of detailed processing as observers “tune out.” In State 2 resources are allocated to the
background environment and the task’s original goals. Inattention in this state, such as crossing
the street in response to peripheral background features of the environment
(i.e. others crossing around you) as opposed to appropriate crossing cues,
results in a sense of “going through the motions.” Finally, in State 3, resources are allocated
to the on-line recruitment and maintenance of task responses. Inattention in this state, such as when you
find yourself aware that you are staring off blankly during class only after
your teacher calls out your name, results from the directing of attention
inward into one’s thoughts and feelings.
Using the
SART, a widely used GO/NOGO task procedure described by Robertson, Manly, et al.
(1997) particularly interesting were
the recorded responses to GO stimuli were extremely fast. From this they inferred that observers were
anticipating the stimuli and therefore responding before even processing
whether it was there. These
anticipations were in-line with the State 2 mind-wandering, as it indicates a
“going with the motions” similar to the example of crossing the street, as
participants respond without viewing the appropriate stimuli. They also suggest that omissions, or the
failure to respond to GO stimuli, indexes State 3 mind-wandering. These are
subsequent states, with recall declining as mind-wandering moves from State 1
to State 3. Such findings insinuate the
possibility of using signatures of each state to provide extrinsic cues to
alert people of mind-wandering at its onset during tasks high in attentional
demand.
Though only
briefly mentioned, I personally found the possibility of effects on those with
disorders in which errors are normally blown out of proportion to be
particularly interesting, as the nature of these illnesses suggests that they
would require an even larger amount of resources devoted to ruminating on performance
following error as compared to normal subjects.
These disorders include anxiety disorders, depression, and OCD. I have
taken many courses focusing on such illnesses, however, have never read about
such research, which would look into how known symptoms can effect mental
processing and in turn, possibly further exacerbate poor performance on the
task from which the scrutinty originated from.
Helton
& Russell (2012) establish a compelling paper that not only critiques
the theories of others, but also tests to see if such critiques are legitimate
by conducting their own study in order to present and compare the contesting
theories. The authors note that there
are two families of theories that attempt to explain the commonly reported
failures to sustain attention due to the vigilance decrement. These two opposing bases of vigilance
decrement directly contradict one another, with one believing the decrement is
a result of resource demand, mental fatigue, or cognitive over-load, while the
other posits that it is due to mindlessness, boredom, or cognitive under-load
experienced during a vigilance task. The
current dominant theory is resource theory, categorized within the prior family
mentioned, specifically arguing that over time, the depletion of cognitive
resources necessary for processing information in vigilance tasks results in
the decrement. However, researchers
such as Robertson et al. (1997) advocates
the mindlessness theory of vigilance, which suggests that reported vigilance
decrements are a result of conscious disengagement or mindlessness due to
inactivity between critical signals. Therefore, under this theory, including content-free
cues should help individuals from disengaging from the vigilance task. However,
when comparing mindlessness theory to resource theory Helton
& Russell (2011) found results that supported the resource theory and
disconfirmed mindlessness theory, as they found that reducing cognitive load of
the task (i.e. by presenting content-related cues) decreased lapses of
sustained attention. Further
disconfirming mindlessness theory, it was noted that in a recent study by Seli
et al. (2012) found that presenting content-free cues did not decrease
vigilance decrement, as Robert et al. (1997) suggested, but instead actually
further impaired performance.
Somewhat similar to mindlessness
theory, though with important distinctions in the way to eliminate vigilance
decrements, Arriga
& Lleras (2011) recently proposed a goal habituation theory, in which
the decrement is the result of the inability of the cognitive control system to
actively maintain the vigilance task goal over a prolonged period of time. The findings from these studies contradict
the resource theory of vigilance, which states that the decrement results from a
depletion of attentional resources during the task. According to their proposal, momentarily
deactivating the task goal (by inserting a brief, unrelated task switch) would
prevent goal habituation over time and therefore eliminate the vigilance
decrement. In their experiment, they
compared performance in a vigilance task across four conditions: control
condition (performed only the vigilance task); a no-switch condition (performed
vigilance task and memory task, in which they had to memorize four digits
before the vigilance task and then were asked to retrieve the digits after
finishing the task); a switch condition (performed the vigilance task and
memorization task listed above, except that they were expected to identify
whether a sporadically presented digit matched the memorized digits during the
vigilance task); and a digit-ignored condition (performed the vigilance task
and were exposed to the digits but asked to only perform the vigilance task).
In the article by Helton & Russel (2012), they re-examine the findings of
Ariga’s & Lleras’ (2011), which had shown that only the switch group
condition (only group with the digit interruption during the task) didn’t
experience vigilance decrement. However,
Helton & Russel (2012) question whether the differences between the switch
group and no-switch group (also had the digit interruption task, but only asked
after completing the task) may be explained by the resource theory, as
participants in the two conditions may have allocated their resources
differently (See Figure 1 below). Figure 1 shows
the results of the switch and no-switch conditions in studies conducted by Helton
& Russel (2012) accurately point out that the difference between the two
conditions following Block 2 could not be a result of goal habituation because
the task switch from vigilance to memory was only presented after block 2, and
then again after block 3. The
researchers mention that this difference in block two between the groups
occurred before the goal switch, however, they do not go further into
explaining what then this could be a result of.
Even if, as the researchers mentioned, perhaps, by chance, those in the
switch group happened to have better vigilance performers than the no-switch
condition (which I do not think is a legitimate explanation, as it would
undermine the concept of randomized placement of participants into conditions,
typically used in all psychological research in order to establish homogeneity
between groups to control for such an effect), this graph still shows that
being in the switch-group eliminated the decrement that is reported by those in
the no-switch group, especially by the differences noted in block 4. The switch group remained rather stable
throughout the entire experiment. Even
if, somehow by chance, the participants in the switch group were in general better
at vigilance task performance, there still would have been a similar trend,
though perhaps not as extreme, in Mean A’ scores as seen in the no-switch
group.
The most important implication of goal habituation is the
idea that, unlike most past research where adding workload during a vigilance
task decreases performance, in these studies this additional workload was found
to eliminate the decrement and therefore aid in task performance.
Helton and
Russel (2012) modeled their study off of that of Ariga & Lleras (2011),
while adding important new elements (self-reports on workload and
task-unrelated thoughts, and a much larger sample size) to strengthen validity
and scope of analysis. This study was
looking to test mindfulness theory, goal habituation, and resource theory. If resource theory prevailed, as
hypothesized, then there would be no beneficial effect of interventions
recommended under the other two cognitive under-load theories on vigilance
decrement. All of the experimental
groups experienced a strong vigilance decrement, as seen over time with a
decline perceptual sensitivity and increase in response latency. However, it is important to note that the
duration time here was much shorter than in the studies by Ariga & Lleras and,
therefore, one could argue that goal habituation takes longer than the tested
time to occur. However, even if this is
the case, the fact that at this shorter interval a vigilance decrement was seen
across all conditions insinuates that goal habituation does not account for all
decrements during vigilance tasks, though it also does not discount the
possibility that over longer periods of time, goal habituation could be useful
to decreasing the lapses in sustained attention during certain tasks. While
there has been much recent research in trying to understand the mechanisms
causing vigilance decrement, such research is still rather new and therefore
even though mounting evidence seems to be leaning towards the resource theory, there
is still much that remains unknown about mind-wandering.
![[2]](http://i.usatoday.net/news/gallery/2009/1209-storm/storm09.jpg){kind=link}
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