I have an excellent example of this, as Im sure we all do. I was fishing a hole for white sea-run perch. They migrate up the James River each spring and there is one in particular of probably hundreds of pools I like to wade to. It drops off after a small rapid to 5-6' deep and is shallow on either bank, probably 15-20' wide. I was standing the at the head, casting downstream with a streamer, which would swing towards the right bank where I was standing and I would draw it upstream. Two or three casts later, a perch took and I began to bring him in, right along the bank where I had previously drawn in the streamer.

Out of no-where, a huge (LM?) bass came and you guessed it, slammed him right off my line and away he went.

Interestingly, he had his pickings of hundreds of perch sitting in that pool, and he had his chance at my streamer on two or three casts that I retrieved right by his nose never knowing he was there. He chose to strike however, when this fish was clearly displaying erratic behavior (fighting me trying to shake free) Clearly, it wasnt the meal, it was the action that triggered him.

Great great posts Buddy, keep them coming!