WASHINGTON  - Playing video games improves manual dexterity among surgeons, making them faster and less likely to make mistakes, US researchers said Sunday. The findings were contained in a raft of research about how video games effect the people who play them, discussed Sunday at the Annual Convention of the American Psychological Association in Boston. "The big picture is that there are several dimensions in which games have effects," including their content, how they are played, and how much, said psychologist Douglas Gentile of Iowa State University. "This means that games are not 'good' or 'bad' but are powerful educational tools and have many effects we might not have expected they could." Gentile presented several studies on video games including one involving 33 surgeons specializing in laparoscopy, the use of a thin lighted tube to inspect and treat various conditions in the pelvic and abdominal cavities. Laparoscopic surgeons who played video games were 27 percent faster at advanced surgical procedures, and made 37 percent fewer errors, compared to their non-gaming colleagues, the study found. Studies involving high school and college students confirmed previous findings about the social effects of playing violent video games, the Iowa State researchers said. Students who played violent games were more hostile, less forgiving, and more apt to view violence as normal, than peers who played non-violent games. But students who played "prosocial" games got into fewer fights at school and were more helpful to other students, the researchers reported. Yet another study, at Fordham University, measured the effect of learning a new video game on problem-solving skills in middle-school-age children and found that "playing video games can improve cognitive and perceptual skills." "Certain types of video games can have beneficial effects improving gamers' dexterity as well as their ability to problem-solve " attributes that have proven useful not only to students but to surgeons," the researchers found.