There are a lot of variables. For example, no one likes to try to see you through your light, it stops their eyes down too much to work well for them.
If you have a very tight beam, when they move their head enough, their eyes can get out of the beam and try to see around it....and if they turn and run, you are just lighting up their ear or the back of their head, etc.
If you have a wall of light, they will find it difficult to move out of the glare, but, the reflected light all over the place can also allow them to see things in the periphery they might have otherwise not been able to...if if you are not one of those things. (Potential escape routes, etc)
Their personality, and the setting, will dictate what will work as far as getting them to stay still. Annoying some people TOO much can PROVOKE a charge, in their attempt to get you to turn the damn thing off, etc.
Some will be intimidated by a large wall of light, and the large party of your compadres or your artillary it might be obscuring. They are overwhelmed, and just give up.
Some will feel a tight hot spot on their face is analogous to where a bullet might go if they misbehave, akin to seeing a laser dot appear on their chest, etc....and behave accordingly.
YOU might want the light to cover enough of an area that you will notice the perp reaching behind him to his waistband, or starting to move his feet, or where he tossed the "stuff", or a buddy still in hiding nearby, and not just his glowing face.
What's your distance? If too far away for your light, you are more like looking at a star than the sun...so there's a glare, but its more easily avoided/not overwhelming and intimidating.
And so forth.
Pics of this would just look like white screens for the most part, and once ~ 100 lux or so is on his eyes, he can't see much either way if he started out in the dark/night adapted, etc....once he closes his eyes to shield them, it doesn't matter much if they are at 100 lux or 1000 lux on his lids, he still can't see much. Even when they do that scrunched up face with the hand like a visor over the eyes...they still can't really see.