When I was young and personal computers where a new thing, there was a study that revealed that many persons did not know what to do with a computer mouse and how to use the pointer on screen to interact with the machine.
Today, probably most everyone knows how to use a mouse, but there are other aspects that computer users still do not understand while developers rely on that knowlege. For example, the recommendation not to force a new window on the user with target="_blank" relies on users knowing how to open a link in a new window or tab if they want to.
When I code links, I often wonder if my users actually know that they can hold the link on their mobile phone until a dialog pops up, or that they can right click to open a context menu and choose to open a link in a new tab. I am worried about this, because if I accidentally push my visitors away from my site at a time when they would have continued shopping, I will lose sales.
Is there research on how many users actually know how to open a link in a new tab?
We should note that many of the recommendations not to force links to open in a new window were voiced before both tabbed browsing and mobile devices. Today, in most browsers with their standard setting,
target="_blank" does not open a new window at all, but a new tab. And on Android mobile phones at least, the back button from a link opened in a new tab closes that tab and returns the user to the originating tab (tested in Chrome, Firefox, Opera and the Android browser), so the device back button works across new tabs on this device.
Also, I while I am certainly not representative, I never use the back button. Read Question Overflow's answer to a related question to learn why. There is a reason why "sites like Google+ and Twitter always open external sites in new tabs", as RobC pointed out in his anser to the same question. Facebook does the same for external links, as I just tested. For that type of site, it may well be the user expected standard behavior of links – and that those sites implement this behavior could be understood as indicating that at least their developers don't think their users know how to open links in new tabs on their own.