In some children who go blind, certain parts of the brain that normally control vision appear to switch jobs and focus instead on sound, a new study has found.  The study, by researchers at the University of Montreal, involved 7 adults who could see and 12 adults who had lost their vision when they were children. Each participant sat in a room with 16 loudspeakers at different locations. The room was designed so that there were no echoes  During the experiment, the speakers irregularly produced sounds. Participants had to point to where the sounds were coming from. Meanwhile, the researchers monitored blood flow in the brains of the participants to see which brain structures were working during the task.  The results showed that five of the blind participants were very good at pointing to where sounds were coming from. In these people, blood flow increased in the visual cortex --- an area at the back of the right side of the brain. This part of the brain is usually associated with vision.  The other seven blind participants showed no increase in activity in the visual cortex. These people didn't do very well at picking out where sounds were coming from. Now, the researchers are looking at whether these people have gained an enhanced  sense of touch instead of sound to replace their lost vision.  The scientists say that their study shows how adaptable parts of the brain can be. The purpose of the experiment described in the passage is to find whether   _  .
blood flow in the brains of blind people is slower blind people have a better sense of sound the sense of touch is better among blind people blind children can regain their sight