In our daily life now, you may often find some people like to do several things together at the same time. They may watch TV while playing cell phones, and they may work while chatting with their close friends. As a new research suggests, people who multitask all the time may be the worst at doing two things at once. The findings, based on performances and self-evaluations by about 300 college students, indicate that many people multitask not out of a desire to increase productivity, but because they are easily distracted and can't focus on one activity. And "those people turn out to be the worst at handling different things," said David Sandy, a psychologist at the University of Utah. Sandy and his colleagues gave the students a set of tests and asked them to report how often they multitasked, how good they thought they were at it, and how sensation-seeking  or impulsive  they were. They then evaluated the participants' multitasking ability with a tricky mental task that required the students to do simple mathematical calculations while remembering a set of letters. Not surprisingly, the scientists said, most people thought they were better than average at multitasking, and those who thought they were better at it were more likely to report using a cell phone while driving or viewing multiple kinds of media at once. But those who frequently deal with many things at the same time were found to perform the worst at the actual multitasking test. They also were more likely to admit to sensation-seeking and impulsive behavior, which connects with how easily people get bored and distracted. "People multitask not because it's going to lead to greater productivity, but because they're distractible, and they get sucked into things that are not as important," Sandy said. Adam, a researcher at the University of California, who was not a member of the research group, said one limitation of the study was that it couldn't find out whether people who start out less focused tend toward multitasking or whether people's recognizing and understanding abilities change as a result of multitasking. The findings do suggest, however, why the sensation-seekers who multitask the most may enjoy risky distracted driving. "People who are multitasking are generally less sensitive to risky situations," said Paul, another researcher not in the group. "This may partly explain why people go in for these situations even though they're dangerous. When Sandy and his colleagues conducted their research, they  _  .
evaluated the academic achievements of the students measured the changes of the students' understanding ability assessed the multitasking ability of the students analyzed the effects of the participants' tricky mental tasks