The two line summary of the lead article is : "Designing for all screen sizes must consider the capacity of the human–device communication channel, which depends on users’ memory, device portability, and screen size."
NN/g argues that the more portable a device, the more likely people are to use it pretty much everywhere, and also the more likely they are to be interrupted while using that device.
Now this is a really interesting bit of information. The attention capacity with a portable device is very different than with a desktop computer. Quoting from a paper published in Mobile HCI that showed that the average session duration on mobile was 72 seconds this contrasts to the average session on the desktop is about twice as long — 2.5 minutes.
The article goes on to look at the cognitive overload that can occur when too much information is stuffed through the mobile channel. The model used being that the brain is something like a computer and can get overloaded. That is partly right but is a lot more complex than suggested.
What the article doesn't say (and I think should) is the impact of ageing on the ability of people to make sense of data overload via mobile.
If you want to find out what happens then have a read of the book I wrote with Kim Walker (sorry for the blatant plug. Dick Stroud