Digital books may have a few advantages over ordinary ones when it comes to kids remembering their contents, according to a new study. Animations, especially ones keyed to verbal interactions, can significantly improve recall of story details — but they have to be done right.

The research, from psychologist Erik Thiessen at Carnegie Mellon University, evaluated the recall of 30 kids aged 3-5 after being read either an ordinary story book or one with animations for each page.

When asked afterwards about what they remembered, the kids who had seen the animated book tended to remember 15-20% more. The best results were seen when the book was animated in response to the child saying or asking something about it (though this had to be done manually by the reading adult) rather than just automatically.

“Children learn best when they are more involved in the learning process,” explained Thiessen in a CMU news post. “Many digital interfaces are poorly suited to children’s learning capacities, but if we can make them better, children can learn better.”

This is not to say that all books for kids should be animated. Traditional books are always going to have their own advantages, and once you get past the picture-book stage these digital innovations don’t help much.

The point, rather, is to show that digital books can be useful and aren’t a pointless addition to a kid’s library. But it’s important that the digital features are created and tuned with an eye to improving learning, and research must be done to determine exactly how that is best accomplished.

Thiessen’s study was published in the journal Developmental Psychology.