Voice controlled interfaces aren't distracting.....or are they?

A colleague of mine sent me an article today describing a new study that found voice controlled interfaces, specifically Ford Sync, significantly helps drivers keep their eyes on the roadway. The benefit of keeping drivers eyes on the roadway during distracting activities is, as VTTI argues, that it reduces crash risk. Interestingly, a number of laboratory and simulator experiments have found that while voice interfaces help keep drivers eyes on the roadway it still does not eliminate impairments observed in driving performance. In-lab results have led researchers to argue that distractions interfere with basic cognitive processes in addition to competing for visual or manual resources. Thus, if you remove competition for peripheral resources (visual and manual) as voice controlled interfaces do there still remains some degree of impairment related to competition for cognitive resources. However, naturalistic studies of driver distraction have repeatedly failed to replicate this result as described in the article. In fact, some studies have found a protective effect of distracting activities on crash risk (recent VTTI study of truck drivers). This begs the question, why the disparity? What differences between these two experimental settings has led to completely different findings? Could it be that drivers employ strategies to handle distractions in naturalistic settings that they do not use in controlled, laboratory settings? Further research is needed to identify the cause of this disparity, but for now I am glad to see that automobile manufacturers are starting to really push technologies aimed at mitigating the effects of driver distraction.