Benefits and costs of distracting the distracted: The effect of concurrent task load on sustained attention while driving

Objective: The objective of this study was to investigate the effects of cognitive and perceptual load on the maintenance of sustained attention and driving performance. More specifically, could increased perceptual load attenuate the decline in sustained attention? Additionally, this study also investigated whether a concurrent task could improve performance particularly when sustained attention was at its lowest under different degrees of perceptual load. Background: Research suggests that engaging in cell phone conversations while driving increases the risk of getting into a crash. However, the monotony of certain driving conditions also increases the risk of crashing. Previous research indicated (see Atchley & Chan, 2011) that engaging in a cell phone conversation reduced monotony, subsequently improving driving performance. This improved performance was attributed to task engagement. Research by Lavie and colleagues (2009; 2010) suggested that higher perceptual loads also increased task engagement resulting in the reduction of task-unrelated thoughts or mind wandering. Higher task engagement is indicative of task-focused cognitions and appraisals which result in better performance. Moreover, high task engagement also increased the amount of resources allocated to the maintenance of sustained attention (see Matthews, Warm, Reinerman, Langheim, & Saxby, 2010). Method: Two driving scenarios were employed in this study to investigate the effects of perceptual load---(1) a congested roadway (high perceptual load) and (2) a monotonous roadway (low perceptual load). Three verbal task conditions were used to investigate the effects of a concurrent task when sustained attention was at its lowest: (1) no verbal, (2) simple verbal, (3) complex verbal. Results: Drivers, regardless of perceptual load, exhibited improved lane keeping performance when sustained attention was at its lowest. However, performance on a visual attention task was poorer for drivers who engaged in a concurrent verbal task. Conclusion: Introducing a strategic concurrent task can improve performance when sustained attention is at its lowest. However, this benefit carries the cost of reduced visual attention to objects in the periphery.