I willing and openly admit that I used to wear hypercolor shirts when I was a kid. Those things were awesome. I never understood why the worked and frankly as a kid I didn't care, but I wanted everything I owned to change color.
My favorite hypercolor shirt was a geko surfing. As it got warmer out, he turned from brown to yellow to green. Loved that frigg'n shirt.
In any case, I came across an article describing hypercolor and how it works. As an adult it is interesting, but I'd give up the knowledge in a hart beat if wearing that stuff became a fad again.
http://www.mentalfloss.com/blogs/archives/53587
Thermochromism, is that like midichlorians?