One of the concepts that we talk about in Combat Focus Shooting classes is that of task fixation: the diversion of attention to a particular sub-activity during an attack. We discuss this specifically relating to looking at the gun while reloading.
The concept is clearly illustrated in this video of a very dynamic simulation during a Craig Douglas ECQC class (one of the few on my "short list" of classes to attend.) Note that the gun fails to fire and suddenly the defender's entire attention is diverted to getting it running again, rather than dealing with his attackers. Craig even mentions that to the student at the end of the exercise, and the student admits to a fatal task fixation.
Many trainers maintain that the best place for the gun is in front of the face so that you can see both it and the threat while you reload. I don't believe that's a rational expectation when the body's threat responses have been activated, and believe instead what will happen is the task of reloading will divert attention completely from the threat in the way that a malfunction did for this fellow.
In the couple of seconds that any normal person is going to take to reload their pistol the threat can shoot or stab quite a few times, or cover a lot of distance to bring himself into contact with the victim. During that time it's more important that you avoid being shot/stabbed/beaten than it is to get a small (and theoretical) advantage in reloading speed. The first order of business is not getting hurt or killed in the process of defending yourself! That sounds silly, but the popularity of techniques that increase your exposure to danger rather than decrease it make it necessary to point such things out.
Instead of looking at the gun, we teach making the reload process a strictly mechanical activity that can be done with the gun out of the direct line of sight to the threat. (The specific ways to accomplish that are beyond the scope of this post, but it's not difficult to do for either autoloading pistol or revolver.) While the gun is being reloaded in that repeatable, mechanical fashion the defender is able to keep an eye on the threat and move, seek cover, or do whatever else is necessary to avoid becoming a casualty.
This is also why we approach the act of malfunction clearing similarly to that of reloading the gun, teaching a non-diagnostic approach to the problem which doesn’t result in the kind of attention diversion that happened in the video.
With the gun in front of the face, as some recommend, I believe (and this video supports my contention) that what will happen is fixation on the reload rather than on the threat. There are other downsides as well, some relating to the perceptual distortions that accompany the threat reaction and how they affect the “look at me” type of reload, but that’s another topic for another time.