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|Title: ||Investigating sleepiness and distraction in simple and complex tasks|
|Authors: ||Wales, Alan|
|Issue Date: ||2009|
|Publisher: ||© Alan wales|
|Abstract: ||The cost of sleepiness-related accidents runs into tens of billions of dollars
per year in America alone (Leger, 1994), and can play a contributing role in
motor vehicle accidents and large-scale industrial disasters (Reason, 1990).
Likewise, the effects of an ill-timed distraction or otherwise lack of attention to
a main task can be the difference between elevated risk, or simply a lack of
productivity. The interaction between sleepiness and distraction is poorly
researched, and little is known about the mechanisms and scale of the
problems associated by this interaction. Therefore, we sought to determine
the effects of sleepiness and distraction using overnight and daytime
sleepiness with various levels of distraction on three tasks ranging from a
simple vigilance task to a challenging luggage x-ray inspection task.
The first and second studies examined overnight sleepiness (7pm to 7am) for
twenty-four healthy participants (m = 23.2yrs old - same for both studies)
using a psychomotor task compared to a systems monitoring task, while also
manipulating peripheral distraction through a television playing a comedy
series. The results showed significant effects of sleepiness on the
psychomotor task and evidence for interactive effects of distraction, whereas
the systems monitoring task showed no changes with either sleepiness or
distraction. Subjects were far more prone to distraction when sleepy for both
tasks, and EEG findings suggest that the alpha frequency (8-13Hz) power
increases reflect impairments of performance. There is a decaying .
exponential relationship between the probability of a subject's eyes being
open as the response time increases, such that longer responses above three
seconds are 95% likely to have occurred with the eyes closed.
The third study used a sample of twelve young (m = 20.8yrs) and twelve older
(m = 60.0yrs) participants, and examined the effects of sleep restriction «
5hrs vs normal sleep) with three levels of distraction (no distraction, peripheral
in the form of television and cognitive distraction as a simulated conversation
by means of verbal fluency task). The task used was an x-ray luggage search
simulator that is functionally similar to the task used for airport security
screening. The practice day showed that speed and accuracy on the task
improved with successive sessions, but that the older group were markedly
slower and less accurate than the younger group even before the
experimental manipulations. There was no effect of daytime sleep restriction
for either the younger or older groups between the two experimental days.
However, distraction was found to impair the performance of both young and
old, with the cognitive distraction proving to be the most difficult condition.
Overall, it is concluded that overnight sleepiness impairs performance in
monotonous tasks, but these risks can be diminished by making tasks more
engaging. Distractions can affect performance, but may be difficult to quantify
as subjects create strategies that allow themselves to attend to distractions
during the undemanding moments of a task. Continuous cognitive distraction
does affect performance, particularly in older subjects, who are less able to
manage concurrent demands effectively. Humans appear capable of coping
Sleepiness and Distraction iv
with a 40% loss of their usual sleep quota or 24-hours of sleep restriction on
complex tasks, but performance degrades markedly on monotonous tasks.
Performances for simple and complex tasks are impaired by distracters when
the effect of distraction is large enough, but the magnitude of impairment
depends on how challenging the task is or how well the subject is able to cope
with the distractions.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Sport, Exercise and Health Sciences)|
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