After reading your analysis, I am confused about how you determined that "that there is a gain of small-to-medium effect size." It seems like once you account for the passive placebo effect you actually showed that there is a small-to-non-existent effect.
That's the net effect. It might be overreaching at this moment to say that the passive studies are complete junk and should be ignored.
Part of the issue here is that the active studies have such a small effect partially because of Clouter 2013 which has a negative effect size - I think, because he didn't report standard deviations, my inferred numbers may exaggerate the strength of his effect, and I haven't been able to get a hold of him yet. So when I got the Sprenger study last week, I just shrugged and added them both in until such time as I get the right numbers.
(It's really frustrating because Clouter is a young techy guy who is on both Google+ and Facebook, it shouldn't be hard at all to get ahold of him! But somehow it's not working out.)
https://www.facebook.com/photo.php?fbid=332127806875228&set=a.316702251751117.76832.316639368424072&type=1&theater seems to be the post through which he recruited the people for his study.
As far as I can see it's possible to leave a comment on that post. If facebook doesn't deliver your message directly to his inbox because you aren't friends that might be a way to get in contact.
This article critically examines previous studies that showed a link between working memory training (specifically via n-back training) and fluid intelligence, finding that the results may not have been as positive as reported owing to a number of factors including the use of a no-contact rather than active control group, and difficulty selecting tests that isolate the impact of working memory on fluid intelligence. The authors also present findings from a new study that show no improvement in fluid intelligence from dual n-back training, visual search training (active placebo) and no training (no contact placebo).
PubMed
Journal Challenged