My understanding is there is some research to support this idea. But I am no expert and people probably have very different individual experiences with it, so I would say look at the information out there and decide for yourself. I will add, I was also very skeptical. I had switched almost entirely to digital books. And while I had noticed I wasn't retaining information as well in recent years (something I pay attention to because a lot of my reading is for research purposes), I chalked it up mostly to getting older. However after reading some articles on the topic I decided to try making a switch and the difference was night and day. I don't think it was just nostalgia. The studies I read put the difference at much greater than the 3-4 times I suggested. And they offered a number of reasons but one of them, which I do find compelling, was that your brain physically indexes the information as it reads a physical book (you may not be remembering the literal pages but something about knowing where you are when you learn the information is helpful). I am not sure if this is what is at play here (maybe it is just the reduced screen distraction). But the difference to me is when I read digital I don't feel like I am sponging up the info the way I do when I read a physical book.