Earlier quoted context omitted.
Upward-firing lights are aimed at the roof to spread the light and create more ambient light. So is primarily used as a down-light by reflection anyway. I'm not sure the left/right shadows are a learned thing from user interfaces. As a kid, long before I got my first computer I was drawing 3D forms. Shadows always was drawn as light came from the upper left. Maybe this is because I draw with right hand so prefer ligh…
Now you've got me wondering if the left/right shadow preference might actually be rooted in other natural phenomena besides human dominant handedness, like something with the rotation of the earth a.k.a. sun setting in the west.
Off topic but I like how you've referenced that infamous IRC meme in your HN handle.