The article discusses how infants develop the ability to use their hands differently when manipulating objects. The researchers studied 90 babies over a 9-14 month period and found that all infants showed improvement in using both hands for different actions. Most babies with a preference for using their right hand for grabbing objects also preferred using their right hand for manipulation. Babies who didn't have a hand preference for grabbing objects also tended to develop a right-hand preference for manipulation. Babies who preferred using their left hand for grabbing objects showed more variation in their hand use for manipulation.