Seems to be freely accessible in fulltext:
The Retention of Manual Flying Skills in the Automated Cockpit (if it does not work, send me a PM, I might be able to get the PDF via the online library at our university).
From the perspective of a humble low-hour-PPL but almost 15-year researcher in the social sciences, the study is niftily designed but has some methodological issues nonetheless. First, the sample size is very low, but this is more of a statement than a critique, as a big sample would be almost impossible/unaffordable to get in this setting. On the other hand, the fact that they report statistically significant findings with this small sample suggests that for the 16 pilots (or 48 sim flights, could not find out by a quick scan which number the calculations are finally based on) suggests that the effects were considerable (read: not so small as to make no practical difference). Second, it is not quite clear to me to which extent the "currency" of the participating pilots in manual flying was accounted for in the analysis, and this could affect the results.
As for the conclusion that basic manual skills do not erode as fast and/or dramatically as the cognitive skills of "staying in the loop", this does not really surprise me. Frankly, having followed the debate on skill erosion owing to automation (just out of interest), I have always been skeptical about the sole emphasis on
manual skills (as opposed to situation awareness and mentally "being on top of the game") for improving safety. (But then again, my frontline experience is arguably nil compared to almost all other folks here.)