Several weeks ago I bought myself a figit spinner. I was playing around with the other day and I notice if I spin it in one diction and hold it up to the light just right it looks like it is spinning in the opposite diction… What makes it look like it’s doing that?
What kind of light? Sunlight? Incandescent light bulbs? LED-bulbs? Fluorescent lights?
If it’s the latter, it could be that the fidget spinner has just the right number of revolutions per second that the pulsing of the light makes it look like it’s moving in the opposite direction. Just like you’ll sometimes see on TV with car wheels or helicopter rotors.
I’m not sure if LED light pulse the same way. And if it’s sunlight or old-school lightbulbs, I can’t offer any explanation.
No, LED bulbs don’t pulse like fluorescents. Although dimmable ones exist they’re pretty much a binary affair because they’re either on or off. 
I should have mention that. I was holding in up to the computer screen light
Well, that light pulses, so that means the explanation for fluorescent lights would apply here too. You can probably see it sort of flickering if you look at the screen with the camera on your phone. The frequency of the pulse would depend on your monitor, but if it’s 60 Hz and your fidget spinner (I’m assuming a three-prong model) is spinning at 20 revolutions per second, it might actually look almost like it’s not spinning. If the speed is a little higher or lower, it would look like it’s moving slowly forwards or backwards respectively. If you really want to check this effect out, you should do it in an otherwise dark room so the screen is the only source of light.
It was a three prong and a two prong and it was fairly dark in my room.