Using a digital device that displays Braille characters, Haben Girma talks with President Obama at a White House ceremony marking the 25th anniversary of the Americans with Disabilities Act. White House photo/Courtesy of Haben Girma hide caption

itoggle caption White House photo/Courtesy of Haben Girma

In sighted people, the part of the brain that recognizes faces is linked to the brain's visual system. But in blind people it seems wired to circuits that process sound. Tina Zellmer/Ikon Images/Corbis hide caption

itoggle caption Tina Zellmer/Ikon Images/Corbis