Report on methods and classification of stress, inattention - sensation
Report on methods and classification of stress, inattention - sensation
Report on methods and classification of stress, inattention - sensation
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D1.1.2<br />
C<strong>on</strong>tract N. IST-507231<br />
It should also be menti<strong>on</strong>ed that mental fatigue is <strong>of</strong>ten measured with st<strong>and</strong>ardized<br />
performance tasks, e.g. vigilance tasks or reacti<strong>on</strong> time tasks (Craig & Cooper, 1992). The<br />
main outcome <strong>of</strong> this research is that performance deteriorates (l<strong>on</strong>ger resp<strong>on</strong>se times, more<br />
lapses) when fatigue increases. However, performance testing can <strong>on</strong>ly be viewed as an<br />
indirect measure <strong>of</strong> mental fatigue. For example, increased mental fatigue can be<br />
compensated by increased mental effort if the individual is motivated. The extra effort will<br />
protect performance <strong>and</strong> maintain it at an acceptable level. The willingness to mobilize extra<br />
effort may also depend <strong>on</strong> the type <strong>of</strong> task. When faced with a boring <strong>and</strong> m<strong>on</strong>ot<strong>on</strong>ous task,<br />
the individual may be reluctant to increase effort, in particular if motivati<strong>on</strong> is reduced<br />
(Hockey, 1997).<br />
Mental effort has been described as energy mobilizati<strong>on</strong> <strong>and</strong> represents a compensatory<br />
strategy to protect performance in the presence <strong>of</strong> increased fatigue due to increased task<br />
dem<strong>and</strong>s or psychological <strong>stress</strong>ors (Fairclough & Houst<strong>on</strong>, 2004; Hockey, 1997). Objective<br />
indicators <strong>of</strong> mental effort are muscle tensi<strong>on</strong> (see above), increased epinephrine (Lundberg,<br />
2000), decreased blood glucose level (Fairclough & Houst<strong>on</strong>, 2004) <strong>and</strong> decreased HRV<br />
(Aasman, Mulder & Mulder, 1987; Meijman, 1997). In HRV, the 0.1 Hz comp<strong>on</strong>ent has been<br />
regarded as being sensitive for mental effort, although some studies suggest that the measure<br />
may not reflect compensatory effort in all situati<strong>on</strong>s (Fairclough & Houst<strong>on</strong>, 2004).<br />
M<strong>on</strong>ot<strong>on</strong>y <strong>and</strong> boredom is <strong>of</strong>ten associated with fatigue <strong>and</strong> effort. According to the <strong>stress</strong>strain<br />
model, m<strong>on</strong>ot<strong>on</strong>y can be regarded as a <strong>stress</strong>or, whereas fatigue reflects the strain (the<br />
resp<strong>on</strong>se <strong>of</strong> the <strong>stress</strong>or). Effort should be regarded as a mediator that may influence the<br />
fatigue resp<strong>on</strong>se. In this c<strong>on</strong>text boredom is an aversive emoti<strong>on</strong>al resp<strong>on</strong>se to an envir<strong>on</strong>ment<br />
that is perceived as m<strong>on</strong>ot<strong>on</strong>ous, <strong>and</strong> have been associated with reduced industrial work<br />
productivity <strong>and</strong> performance (Davies, Shacklet<strong>on</strong>, & Parasuraman, 1982; O'Hanl<strong>on</strong>, 1981).<br />
Boredom is highly situati<strong>on</strong>-specific <strong>and</strong> is immediately reversible when the situati<strong>on</strong> changes<br />
<strong>and</strong> becomes more stimulating (O'Hanl<strong>on</strong>, 1981).<br />
M<strong>on</strong>ot<strong>on</strong>y is usually defined with reference to the sensory stimulati<strong>on</strong> that is present in a<br />
specific situati<strong>on</strong>. A m<strong>on</strong>ot<strong>on</strong>ous situati<strong>on</strong> is characterized by low variati<strong>on</strong> <strong>and</strong> lack <strong>of</strong><br />
alerting stimulati<strong>on</strong> (Thiffault & Berger<strong>on</strong>, 2003). M<strong>on</strong>ot<strong>on</strong>y is an “exposure” variable that<br />
can be quantified through observati<strong>on</strong> <strong>and</strong> task analysis. It is not possible or meaningful to<br />
measure m<strong>on</strong>ot<strong>on</strong>y with subjective <strong>methods</strong> or physiological markers. However, since there<br />
are probably individual differences in the tolerance to m<strong>on</strong>ot<strong>on</strong>ous situati<strong>on</strong>s, physiological<br />
<strong>and</strong> subjective resp<strong>on</strong>ses <strong>of</strong> m<strong>on</strong>ot<strong>on</strong>y exposure would still be relevant to study. Thus,<br />
m<strong>on</strong>ot<strong>on</strong>y should be an important modifier <strong>of</strong> the relati<strong>on</strong> between fatigue/sleepiness <strong>and</strong><br />
accidents/performance errors. A typical m<strong>on</strong>ot<strong>on</strong>ous <strong>and</strong> boring situati<strong>on</strong> is when the<br />
dem<strong>and</strong>s for sustained attenti<strong>on</strong> are high but little informati<strong>on</strong> is c<strong>on</strong>veyed. Hence, m<strong>on</strong>ot<strong>on</strong>y<br />
can be regarded as a source <strong>of</strong> task-induced fatigue that c<strong>on</strong>tributes to performance<br />
deteriorati<strong>on</strong> <strong>and</strong> “strengthen” the fatigue resp<strong>on</strong>se. M<strong>on</strong>ot<strong>on</strong>y is c<strong>on</strong>sidered to be a critical<br />
factor in transportati<strong>on</strong>, especially during uneventful motorway driving, but also in<br />
m<strong>on</strong>itoring <strong>of</strong> industrial processes.<br />
If the individual at the same time is exposed to other fatigue or sleepiness c<strong>on</strong>tributing factors,<br />
such as sleep loss or night work, the m<strong>on</strong>ot<strong>on</strong>y induced increase in fatigue may have dramatic<br />
c<strong>on</strong>sequences <strong>and</strong> increase performance decrement. On the other h<strong>and</strong>, if the individual is<br />
alert (no sleep loss, daytime work) before the m<strong>on</strong>ot<strong>on</strong>ous situati<strong>on</strong> starts, the effect <strong>on</strong><br />
performance may be relatively weak <strong>and</strong> the reached fatigue level will be moderate. The<br />
individual’s resp<strong>on</strong>se to m<strong>on</strong>ot<strong>on</strong>y is usually to mobilize extra energy through effort, at least<br />
if motivati<strong>on</strong> is high. This can be very <strong>stress</strong>ful <strong>and</strong> the cost for the increased effort may result<br />
in increased aut<strong>on</strong>omic activati<strong>on</strong>, e.g. decreased HRV <strong>and</strong> increased muscle tensi<strong>on</strong>. In this<br />
30/08/2004 15<br />
Karolinska Institutet