A computer program called Eugene Goostman, which simulates a 13-year-old Ukrainian boy, is said to have passed the Turing test at an event organised by the University of Reading.
The test investigates whether people can detect if they are talking to machines or humans.
The experiment is based on Alan Turing's question-and-answer game Can Machines Think?
No computer has passed the test before under these conditions, it is reported.
The 65-year-old Turing Test is successfully passed if a computer is mistaken for a human more than 30% of the time during a series of five-minute keyboard conversations.
On 7 June Eugene convinced 33% of the judges at the Royal Society in London that it was human.