I'd like to make a small contribution to what is already an excellent discussion.
1. Everything said in these posts matches to my pet theory which I would state as follows:
"Satiation and competition drive selectivity"
Meaning.... Many fish are opportunists, which will sample a variety of offerings. If a fish is well fed, he would still eat, but is less likely to select an odd or unfamiliar offering. He may still agressively take an offering, in spite of being full, if he believes the offering is realistic and there is direct, appreciable competition for said offering. Negative reinforcement has to then be factored in. Each fish's capture event, especially to a particular offering then subtracts from his liklihood of eating depending on the genetic makeup and intelligence of a particular fish.
The tilapia behavior follows this to a tee. So do Meadowlark's hard to catch LMB.
If you want a fish to be catchable you need to account for all factors.
Hunger, genetics, conditioning, presentation and health of the fish all play a part, with no one factor entirely dictating the response.
