oh my gosh this thread just made me so happy because I was wondering the same thing! first time I ever experienced the light bulb brightening was when I was deep in concentration. There was only one lamp on to my left and suddenly the whole room became much more illuminated. I turned to look at it, still thinking deeply about something else and the longer I stared, the brighter it got. Now whenever I'm near a light, I like to have some fun with it