New York, May 27 (IANS): Human babies can understand basic abstract relations - whether two objects are the same or different - even before they learn the words to describe such relations, new research has found.

Analogical ability - the ability to see common relations between objects, events or ideas - is a key skill that underlies human intelligence and differentiates humans from other apes.

The researchers found that infants are capable of learning the abstract relations of same and different after only a few examples.

"This suggests that a skill key to human intelligence is present very early in human development, and that language skills are not necessary for learning abstract relations," said lead author Alissa Ferry who conducted the research at Northwestern University in the US.

To trace the origins of relational thinking in infants, the researchers tested whether seven-month-old infants were shown pairs of items that were either the same -- two Elmo dolls -- or different -- an Elmo doll and a toy camel -- until their looking time declined.

"The infants in our study were able to form an abstract same or different relation after seeing only six-nine examples. It appears that relational learning is something that humans, even very young humans, are much better at than other primates," said co-author of the study Dedre Gentner, professor of psychology at Northwestern University.

For example, she noted that in a recent study using baboons, those animals that succeeded in matching same and different relations required over 15,000 trials.

The study was published online in the journal Child Development.