These silencing events begin to occur after the dolphins slowly reduce the amount of time they spend using sonar. When in enclosed spaces, their sonar signals bounce off walls and back toward them, which can cause psychological effects similar to animals with good eyesight being enclosed in mirrors. This eventually creates self-consciousness in the dolphin, which can lead to vulnerability in captivity (Reiss 2000). It has been stated that when a dolphin is more aware of its presence in its environment, it is more likely to determine the difference between pleasant and unpleasant situations (Reiss 2000). In addition to their self-awareness, captive dolphins have also shown signs of aggressive behavior. There have been reports of injuries to NMFS involving people who participated in sessions with dolphins who suffered broken bones, bites, bruises, and even hospitalizations (Rose