Neat illusion.
But that probably isn't the cause of people not "seeing" motorcycles. The main reason is they don't EXPECT to see motorcycles, because they are out of the ordinary... people are in-tune with the 99.9% not the 0.1%. The brain kinda filters out motorcycles in many cases. It is one of the main reasons for headlight-on laws for motorcycles.
The other problems are that a motorcycle is small, so there is less to see, and is it much more difficult for a car to judge where and how fast a motorcycle is going because it is horizontally so narrow. This is why I advise: 1) You should never blind cars by running with high-beams on [and lights should be adjusted properly] 2) Having MORE lights is helpful 3) The wider the spacing is between the lights, the better 4) Having yellow lights, in addition, is useful. 5) Having side lights is also useful. 6) Using reflective tape and/or gear is useful (for night).
Another visibility trick is to "wiggle" or "waggle" the bike at a car to make sure they see you- a tight left/right/left/right weave motion is caught by the eye far better than what might look light a single dot of light. Horizontal and vertical motion greatly enhances visibility. NEVER FLASH YOUR HEADLIGHTS at oncoming cars that might turn in front of you.... this can be mistaken as yielding the right of way.
Agree 100% but there are still a lot of variables that can create illusions. Time of day, position of sun, other moving objects etc... I think lighting is critical as well and I really like the side marker write up you did. I plan to do that as soon as time permits but I will probably go a little different route.