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Understanding drivers motivation to take a break when tired

Williamson, A, Friswell, R, Olivier, J, Grzebieta, R H, Zeller, R (Peer reviewed)

Driver Psychology / Human Factors

ARSC conference 2015

Evidence shows that drivers are aware of and can report increasing fatigue while driving and most importantly can detect the likelihood of falling asleep prior to crashing. Drivers reporting high likelihood of falling asleep are four times more likely to crash and nine times more likely to cross the centreline in a driving simulator. This shows that drivers can make an informed decision to drive or not drive when tired. The question is why tired drivers don't always make the safe choice. This study investigated the impact of motivational factors on drivers' decision to respond or not to fatigue while driving. The study examined two motivational influences affecting fatigued drivers: fear of fatigue-related crashes and the need to finish the trip in a specified time. The relative strength of influences was manipulated through monetary incentives. Three groups of 30 tired drivers did a two hour drive in a simulator in one of three conditions: Safety motivation - drivers were informed that an amount would be deducted from $100 whenever they had a serious safety incident; Time motivation - drivers were told that money would be deducted from their $100 if they were slower than expected; No motivation - drivers were paid $100 at the end of the trip regardless of safety or time. Preliminary results showed that Safety motivation was effective: many drivers took breaks and driving performance was improved compared to No motivation. Time motivation was also effective in making drivers take fewer breaks and complete the trip earlier.