Babies learn to 'spot-the-ball'

Babies learn objects do not disappear if they cannot see them by experience

Babies can anticipate movement - enabling them to play "spot-the-ball" at just four months old.

Experts had been uncertain how babies understood that an object was moving in a certain direction - even if it disappeared from view briefly.

Some had suggested that babies had an innate ability to track objects.

But research in the Proceedings of the National Academy of Science showed it develops at four months, and babies master the skill by six months of age.

In the research, babies were shown an animation of a ball moving across a computer screen.

At times, the trajectory of the ball was obscured by a box on the screen.

Scientists followed their line of sight by using a camera to track their eye movements, with crosshairs on the screen indicating where they were looking.

The four-month-olds rarely looked towards the area where the ball should re-emerge.

But the six-month-olds frequently anticipated where the ball would appear.

Training

The scientists then tested their theory that the skill was learnt by showing the four-month-olds the same animation without the boxes, so they could follow the ball through its whole trajectory.

These babies were then more likely to anticipate where the ball would reappear when they were shown the original animation again.

The six-month-old gained no added ability when they were given extra training.

The researchers, from New York University, say their research suggests understanding that objects do not disappear completely when they cannot be seen, and that they have a permanence, is a learnt, rather than an innate skill.

Writing in the Proceedings of the National Academy of Science, the researchers led by Dr Scott Johnson, said: "In addition to highlighting potential contributions of rapid associative learning in four-month-old infants, our results reveal that representations of object continuity are acquired by six months of age in the absence of direct experience with the unoccluded trajectory.

"Presumably, this experience is induced by viewing the many instances of object movement, occlusion, and disocclusion that are part of the natural visual environment."

They added: "By six months, infants have had sufficient exposure to occlusion over the normal course of development, which provides appropriate experiences to support formation of rudimentary object concepts."