I guess I should tell you what we're doing here. There's a million-dollar camera mounted in the belly of the airplane and I'm contracted as a photo survey pilot to fly it around and take pictures. The mystery crosshairs and dot from a couple of days ago are part of the pilot guidance screen. Let me explain that.
The crosshairs is only one small part of the guidance system. While I am on line, the main screen depicts a red line for the track I am supposed to follow and an amber line with a green airplane on it for the track I am on. There are also two other parallel lines denoting out of bounds to either side of the central red line. That only gives my lateral positioning over the ground. I also have to keep the camera level and maintain the proper groundspeed and altitude. Groundspeed and altitude are poorly represented with tiny-font tapes slightly too far from my area of focus, and the targets not marked on the tapes but hidden off to the side, in among too many other unnecessary pieces of data. But the pièce de résistance is that little green dot.
With the green dot centred exactly on the crosshairs, the airplane is perfectly level and the camera pointed straight down at the ground. (The operator adjusts the camera to maintain "level" for different cruise attitudes at different power settings). You see that in my representation the green dot is slightly above the line and a little bit further towards the left. Many of you guessed that it represents a needed change in aircraft pitch attitude and bank angle. Did you guess that I have to steer towards the dot, by pitching up slightly and rolling left a bit more? You would be wrong. Did you guess that I have to "fly the dot" back to the centre by pitching the nose down ever so slightly and rolling to the right? You would also be wrong. Amazingly, one person did get it, albeit on his fifth guess, but you've mostly demonstrated the natural way to think about it. This is not a natural interface.
The configuration shown indicates that I should pitch down slightly (away from the dot) and roll left slightly (towards the dot). They are both minuscule corrections. The airplane is pretty much wings level in a level pitch attitude, but it is asking me to apply the tiniest bit of forward pressure on the control column and a touch of roll to the left. I was completely baffled as to how any sane human being could think this was a reasonable interface, until I showed it to a computer programmer. He explained, "If the dot is up, the nose is too high. If the dot is to the left, the left wing is too high." It makes perfect sense, so long as you don't know how an airplane actually works. And thanks to the amazing adaptability of the human brain, I am able to use this thing. I don't know if I'll be able to fly IFR on an attitude indicator anymore, but we shall see.
The crosshairs depiction on my screen is at the bottom left, far enough away from the lateral placement line that I can just see both at once, and far enough from the altitude information that I almost never see that. If you're thinking, "That's an awfully pale dot colour. Why didn't you use a brighter green?" then you are thinking something that I have spent several hours thinking. The dot on my screen is actually paler than the one in the simulation above, and the crosshairs on my screen are tiny. If the light is bright, I can't see the dot at all, and because of how pale it is, I have to focus on it to see it, not rely on peripheral vision. When the dot goes "too far" (I don't know how that is defined) from the centre in any direction it turns red, which is helpful in that the colour change allows me to see it, but bizarre in that in bright light it's like playing whack-a-mole, just flying along wondering where the red dot will pop up next.
It is a lot like playing a video game all day. I make Pac Man jokes all the time. "Maybe this dot will give me the energy boost!" I loved all your creative explanations of the nature of the dot.