There's still a need for decent studies that assess their impact on behaviour. One such study has emerged from Denison University, where Robert Weis and Brittany Cerankosky have tested what happens when you give young boys, aged 6-9, a new video game system.
They found that after 4 months, boys who had received the games had lower reading and writing scores than expected, failing to improve to the same degree as their console-less peers. They also faced more academic problems at school. At first this might seem like support for the rewired brains of Greenfield's editorials, but the reality is much simpler - the games were displacing other after-school academic activities. While some children were finishing their homework or reading bedtime stories, those with games were mashing buttons.
via scienceblogs.com