The biorhythm machines of the 1970's were certainly akin to fortune-telling machines, but with all those lines and numbers, they gave the impression that their predictions were actually steeped in cold, hard science. No sir, this wasn't any kind of Zoltan hocus-pocus…after all, if you were staring down at a custom-made graph that looked like something straight out of your geometry class, you had to be staring at the truth. Right?
The main tenet of biorhythm states that there are three cycles which affect our lives: the physical, the emotional and the intellectual. Each cycle starts at a zero mid-point when we are born, then travels above and below the zero line over the course of our lifetimes. If a particular cycle is at a high point on a certain day, then on that day, we will do things pertaining to that cycle…well, we'll do them better. A discernable spike in your "physical" cycle, for instance, means it's a good day for a little Skee-Ball.

To enjoy the full Biorhythm arcade experience, a person paid his coinage fee, punched in his birthday, and these machines spit out a personal, for-his-eyes-only chart, by which he could tell the high and low days for each of his cycles. Forget the big stuffed elephants, these machines provided an arcader with a roadmap on how to live his life. All that for some loose change? What more could you ask for?