Professor Vasu Reddy, of the University of Portsmouth in UK, has found most babies aged two to four months understand they are about to be picked up the moment their mothers come towards them with their arms outstretched and that they make their bodies go still and stiff in anticipation, making it easier to be picked up.
This is the first study to examine how babies adjust their posture in anticipation to offset the potentially destabilising effect of being picked up.
"The results suggest we need to re-think the way we study infant development because infants seem to be able to understand other people's actions directed towards them earlier than previously thought," he said.
"Experiments where infants are observers of others' actions may not give us a full picture of their anticipatory abilities," Reddy said.
More From This Section
The findings could also be used as an early indicator of some developmental problems, including autism. It was reported by researchers in 1943 that children with autism don't appear to make preparatory adjustments to being picked up.
In both, babies were placed on a pressure mat which measured their postural adjustments during three phases: As their mothers chatted with their babies; as the mothers opened their arms to pick them up; and as the babies were picked up.
The results revealed infants as young as two months made specific adjustments when their mother stretched her arms out to pick them up.
Between two and three months of age the babies' gaze moved from mostly looking at their mother's face to often looking at her hands as she stretched her arms out towards them.
The results found that from as early as two months babies make specific postural adjustments to make it easier to pick them up even before their mother touches them.
The study also found babies learn to increase the smoothness and coordination of their movements between two and four months, rather than develop new types of adjustment.
The research is published in the journal Plos One.