I think it's the intention that counts. When I'm reading on a multi-purpose device like a tablet or smartphone, I can get easily distracted and have an urge to

I think it's the intention that counts. When I'm reading on a multi-purpose device like a tablet or smartphone, I can get easily distracted and have an urge to do something else. Some days however I can get lost in a book on it. The kindle is unique in that you can't do anything but read on it. Same thing with a physical book. I also believe that the physical traits such as how far you are in a book and the smells / sights can also have plenty to do with it. You don't get that with a digital equivalent. With all that said, I don't see any difference in comprehension. Some books are simply better on physical and some are simply better on digital. Using Clayton Christensen's Jobs To Be Done Framework, by giving your devices a job, the more successful you'll be in the outcome you seek. For example I give my iPad Mini a job to be done of being my e-reader at night. And it works wonderfully as I don't swipe through random apps if it's already my intention to read.