London: A new study shows that a pet dog doesn't care if its owner is nutty. Researchers at Max Planck Institute for Evolutionary Anthropology and at Harvard University have claimed that dogs don't really pick up on rationality.

Behavioural researcher Claudio Tennie and his colleagues said that previous experiments that proved dogs can differentiate between rational and irrational behaviour assumed that dogs are able to learn by copying behaviours, which is not at all proven.

"There doesn't seem to be any social learning in dogs. We couldn't find imitation in dogs. Dogs completely failed to do that," a news channel quoted Tennie as saying.

His team have tried to find such behaviour in dogs - like whether a dog can learn a dog-human ball game by watching - but found none.

To examine the matter more closely, Tennie and his team duplicated an earlier experiment to see if it was just the presence of a ball -- a highly interesting object to most dogs -- that was actually causing dogs to seem to distinguish between rational and irrational acts.

"(Tennie and his colleagues) have convincingly shown that is the sight of the ball, rather than assessing rationality of choice of means as a function of the context, that primes the mouth action," said Gyorgy Gergely of Central European University's Cognitive Development Center in Budapest.

They then tested whether dogs could distinguish between a human pointing to food with their toe or fingers, with and without hands free (rather like the original experiment with human children).

What they found is that the dogs didn't notice the rationality of the act, but took the clue in a more pragmatic way and found the food either way. Their experiments are reported in the January issue of the journal Animal Behaviour.