So was I. This led to more research which led me to understand this difference between Phi and Beta:
What's the difference?
Well, Phi is movement perceived when our brains fill in the gap with something. In a sense, our brains create an object that covers the dots. This works with any colored background or shape.
Beta, on the other hand, is movement perceived when an object changes location/shape/size/angle/etc... This is where a new dot is shown slightly ahead of the previous dot, and so it seems like the dot is moving across the screen. If I made the dots get larger, the dot would appear to be getting closer to you.
There you have it: The difference between Phi and Beta.
And, no, they aren't dormitories or fraternities at your local college. Of course, if you meet someone from such a place, you can ask them if they know the difference between the two.
Your Media Production Mentor