As an interface designer, and just as a designer in general, I often notice that I feel the need to place things slightly off-center in order to make them appear centered and balanced, due to the items having uneven volume distribution.
Consider a play button which is placed in a box:
Months after asking this question I was developing video controls and realized this was the perfect example. This image is centered geometrically, but in my interface, I pushed the icon about 15% further to the right than its actual geometric center in order to center it based on volume because geometrically centered (as you can observe in the above image) doesn't feel quite right.
I usually just guess at centering an icon volumetrically, but I bet the proper center could be determined mathematically, hence my curiosity as to the name, in case I might find a tool or plugin to help me do this with my design tools such as InDesign.
Off the top of my head I'd call it "Volumetric Centering", but that's just a guess. Is there an official name / term for this technique?