A joint US-UK research project says it has evidence suggesting that nine-month-old babies can learn about real-life objects from realistic photographs. By contrast, they say pop-up books are bad.
Researchers at the Royal Holloway, University of London, and the University of South Carolina say babies can make a connection between flat images, such as photos, and tangible objects from the age of nine months.
Until now, it was thought this happens only months later in a baby's development.
"Babies are probably smarter than most parents think," says co-author Dr Jeanne Shinskey, at Royal Holloway's Department of Psychology.
"The research tells us that it's possible in the first year of life for infants to learn indirectly about a real thing from a two-dimensional, highly-realistic photograph," she says.
During the Royal Holloway study, 30 infants aged between eight and nine months old were shown life-sized photographs of objects, which the researchers thought infants would most likely recognize.
They were shown the images for about one minute.
The images were then taken away and the babies were "given the choice between two objects - a real-life version of the toy in the photograph and a toy of another shape and color."
And the researchers monitored which toy the child went for first.
2-D good, 3-D bad?
The results surprised Shinskey and the reports co-author, Liza Jachens.
"More often they went for the new thing, the green block of a different shape," says Shinskey.
"What this tells us is that they remember the orange block from having seen a picture of it and they are kind of bored with that, and they would prefer to explore the new green block."
Shinskey says this means babies can retain the two-dimensional image in their minds even after the object has been taken away.
Well before their first words and their first birthday, babies start to learn about the real world from picture books, Shinskey says.
But while she says there is little research into infant learning under the age of 12 months, other research suggests that "baby books that have manipulative features in them like pop-ups and pull tabs can actually hinder a child's learning."
This would suggest that flat - two-dimensional - images are better for early learning.
Books that have three-dimensional elements, says Shinskey, may distract infants from learning.