True indeed. But painting involves steady motion of the hand whereas interaction with computers requires much less motion and thus is far more straining for our

True indeed. But painting involves steady motion of the hand whereas interaction with computers requires much less motion and thus is far more straining for our arms. Basically, it all revolves around strain: We don't want to strain our arms by holding something up in the air for a long time and we don't want to strain out neck by holding the head in an imbalanced position for a long time. As long as the head can sit more or less balanced on the neck, we are fine. Hence, if we sit back, the comfortable position for the head is to look slightly downwards compared to the rest of the body. However, the head actually is still upright, only the body is at an angle. Of course, we can still move our eyes without straining the neck muscles. We are fine with looking something like 45° downwards. (Actually, we are most comfortable with looking at the ground a few dozen meters/feet away. That is the natural looking angle.) Hence, monitors should sit slightly below eye level (for practical reasons, they usually extend from there to desktop level). Manual input devices should be located slightly below elbow level one forearm-length in front of the belly. It will be interesting, which manual input devices will sit there in the future. But I would guess that they will always sit there, and not on the display.