It has been proposed that cell phone use while driving may provide benefits during monotonous trips (Pope, 2009). Previous research has shown that voice communication enhances mental alertness when driving long distances (Drory, 1985). A recent study showed that a strategically placed verbal task may improve performance during monotonous driving conditions (Atchley & Chan, 2011). Nevertheless, the interaction of monotony and fatigue in different driving conditions when engaged in more personalized conversation has not been well-explored. The present study tested whether the effects of cell phone use on driver performance and subjective state differ depending on the fatigue induced by qualitatively different driving scenarios: passive fatigue and control conditions (see Desmond & Hancock, 2011). Passive fatigue appears to be associated with low workload (underload) conditions, in which cognitive demands on the driver are low (e.g., monotonous conditions characterized by low traffic density, minimal steering demands, and constant speed).
Results of this study showed that the passive form of fatigue appears to be particularly hazardous in driving. Further, cell phone conversation did not serve to reduce the subjective experience of passive fatigue; rather, it added worry about matters unrelated to the driving task. Regarding performance, cell phone use moderately improves vehicle control, but did not improve brake response times or crash rates. Moreover, cell phone conversation appears to reduce drivers’ insights into their own performance impairments when passively fatigued, which is a potentially hidden danger. Finally, certain personality types are more prone to passive fatigue.