Looking at something indeed doesn't mean paying attention to it. That's why head-up displays can be dangerous (just like handsfree phone usage).

Daniel Simons, a professor in the Department of Psychology at the University of Illinois, says this in his episode of the You Are Not So Smart podcast:

http://youarenotsosmart.com/2012/04/24/yanss-podcast-episode...

Head-up displays are discussed starting at 12:31.

If I remember correctly, pilots were at danger to miss planes on the runway while using a head-up display.

"Even pilots use it – it's safe." Is it?