Learners have changed as a result of their exposure to technology, says Greenfield, who analyzed more than 50 studies on learning and technology, including research on multi-tasking and the use of computers, the Internet and video games. Her research was published this month in the journal Science.
Reading for pleasure, which has declined among young people in recent decades, enhances thinking and engages the imagination in a way that visual media such as video games and television do not, Greenfield said.
How much should schools use new media, versus older techniques such as reading and classroom discussion?
"No one medium is good for everything," Greenfield said. "If we want to develop a variety of skills, we need a balanced media diet. Each medium has costs and benefits in terms of what skills each develops."
Schools should make more effort to test students using visual media, she said, by asking them to prepare PowerPoint presentations, for example.
"As students spend more time with visual media and less time with print, evaluation methods that include visual media will give a better picture of what they actually know," said Greenfield, who has been using films in her classes since the 1970s.