When I started fly fishing as a kid back in the 50's, you only used bobbers on a cane pole. The so called indicator was yet to be invented. By the time they came along, I was well into sight fishing. Most indicator fishermen are so in tuned to watching the indicator, that they fail to notice what is actually happening in the water around them. Them little flashes that you see, out of the corner of your eye from time to time, are usually a fish tasting your fly then spitting it back out as the indicator travels on undisturbed. I think that the person who invented the indicator also had a role in the self driving car.