After crawling cites a bit from Wikipedia and other sources it seems like there are, at least, studies indicating successful improvements in working memory capacity from cognitive training. The DNB task is incredibly demanding on working memory, so it seems likely it is successful at least for improving that.
Furthermore it seems that some researchers suspect deep connections between working memory capacity and fluid intelligence, so there’s still a plausible connection here—which makes the methodological issues even more frustrating.
After crawling cites a bit from Wikipedia and other sources it seems like there are, at least, studies indicating successful improvements in working memory capacity from cognitive training. The DNB task is incredibly demanding on working memory, so it seems likely it is successful at least for improving that.
Furthermore it seems that some researchers suspect deep connections between working memory capacity and fluid intelligence, so there’s still a plausible connection here—which makes the methodological issues even more frustrating.