A new study out of Iowa State University finds that people who play video games for 40-plus hours a week have a harder time focusing on certain tasks than those who play just a few hours a week, CNET reports. Published in the latest issue of the journal Psychophysiology, the study also supports research published earlier this year that found a positive correlation between video game addiction and Attention Deficit Disorder (ADD). What is still unclear is whether the propensity to play video games for several hours a day the cause, or the effect, of attention problems. The study shows a correlation, but more research is required to identify the true culprit, researchers say. "Right now the data we’re reporting in this study [are] really susceptible to the chicken-and-egg problem," said Rob West, an associate professor of psychology and director of the Cognitive Psychology Program at Iowa State. "It might be that playing the games is actually producing this effect, but it could also be that individuals who, for whatever reason, like to play 40 hours a week also have this mode of attending to this kind of information in the world."