Aliens may be using a cosmic version of Twitter to contact us - but for decades we have been missing their "tweets", it has been claimed.
ET is more likely to be sending out short, directed messages than continuous signals beamed in all directions, say experts.
"This approach is more like Twitter and less like War and Peace," said Californian physicist Dr James Benford, president of Microwave Sciences.
He and twin brother Gregory, an astrophysicist at the University of California, Irvine, looked at the Search for Extraterrestrial Intelligence (Seti) from the aliens' point of view.
They concluded that Seti scientists may have been taking the wrong approach for the past five decades.
Up to now the strategy adopted has involved listening out for unusual blips or bleeps from targeted nearby stars.
Despite 50 years of searching, no-one has yet been able to come up with evidence of an extraterrestrial signal. However, many scientists are convinced we cannot be alone in the universe.
"Whatever the life form, evolution selects for economy of resources," said Gregory Benford. "Broadcasting is expensive, and transmitting signals across light years would require considerable resources."
Writing in the journal Astrobiology, the Benfords' claim that an alien civilisation would strive to reduce costs, limit waste and make its signalling technology efficient.
They propose that ETs' signals would not be blasted out in all directions but pulsed and narrowly directed in the one to 10 gigahertz broadband signal range.