During a research experiment, a shark was placed into the large tank of water and then some small fish were released into that tank. As you would expect the shark quickly swam around the tank, watched the fish and then ended up eating all of them. Then a strong piece of fiberglass was inserted into the tank. This would create a division between where the shark started and where the smaller fish started. Again the shark quickly attacked but this time the shark went in straight into the fiberglass divider and bounced off. It tried this several times again and again and again until it became tired and weakened. Meanwhile, the fish on the other side of the divider carried on swimming peacefully. After about an hour the shark finally gave up. This experiment was repeated several dozen times over the next few weeks, where the shark became less aggressive every single time. It got to the point that the shark stopped trying to attack and eat the fish at all. The fiberglass was then removed out of the tank, and to their amazement, the shark did not attack. The shark had been trained through habit that a fiberglass divider was there and that it would bounce off and therefore didn't even consider it. At the same time, the small fish freely swam wherever they wanted.