SafeSpeed wrote:
This is supposed to be science at the layer of setting research objectives. The big problem with the existing literature is that few tasks enable those involved to adjust their own work rate and stress level, and few tasks require the uninterrupted long term vigilance required by driving.
Hi
Just reading this topic. The relationship you indicate is very much what I feel. Plus it explains very well what one feels instinctively.
I first read about this in human factor courses for airline pilot students. However this kind of curve is everywhere where human factors are studied...
except in road safety, strangely...

probably for the reasons you mention....
In my books, as I remember it, two factors were studied, both of which are linked and follow a similar curve: stress and workload.
Now you've talked about stress, but I've not seen any mention of "workload". Maybe this notion would make things clearer?
To sum up things:
- no stimulation, no workload at all => falling asleep
- low workload => boredom, tendency to do other things, poor concentration
- "average workload" => sentiment of well-being, good mental performance
- high workload => feeling of saturation, tiredness begins to develop quickly: this serves as a warning for the next phase:
- too high workload => task saturation, breakdown of performance, fast exhaustion.
As fas as your curve is concerned, I wouldn't mention "risk taking" & excitement since it is ambiguous. Over-excitement (clouding the judgement and leading to risk-taking) is something else, I believe. On the other hand, once task saturation has been reached, one is forced to act with precipitation and may make a dangerous action - or get to the point where one fails to act at all.
Hope all of this helps, the subject is complex so it's hard getting around it in one post. If you want more precise information about my readings, don't hesitate to ask, I'll see what I can do.
Regards.