One thing to note is that the anecdotal evidence leads people to believe that our cognitive functions are highly malleable. In this article, and in other reporting on attention spans and focus, the conclusion seems to be that new behavior reflects some change in our brain structure. I'd like to see more actual scientific literature on how directly new behavior physically alters our brain structure. The article points us to one study suggesting that the spatial regions of the hippocampus of London taxi drivers are more developed than those of bus drivers. Researchers have concluded that because bus drivers follow the same routes every day, and taxi drivers are required to know a much greater layout of the city, the taxi drivers' brains are more developed for spatial reasoning. At first glance, this seems like a perfect example of "desirable difficulty" at work.
Further, the article references the work of mid-twentieth century psychologist Edward Tolman. His lab experiments with rats in mazes has been influential in psychological circles, and introduced the theory that humans, like rats, have a "cognitive map" in two parts: "strip maps" and "comprehensive maps." "Strip maps" are a simple understanding of how to get from one point to another. "Comprehensive maps" are a more robust form of the strip map, after a larger spatial context has been learned through deeper experience and knowledge of place. As we continue to think about learning and technology, I think Tolman's theory of "congnitive mapping" might be usefully paired with what we've been learning about "desirable difficulty."