No computer has passed the test by fooling 30% of its human interrogators
An experiment has been taking place in Berkshire to see if robots are capable of intelligent thought.
Scientists at the University of Reading tested five machines to see if they could pass themselves off as humans in text-based conversations with people.
The test was devised in 1950 by British Mathematician Alan Turing, who said that if a machine was indistinguishable from a human, then it was "thinking".
One robot, Elbot, came close on Sunday by reaching 5% below the pass mark.
No robot has ever passed the Turing Test, which requires the robot to fool 30% of its human interrogators.
During the experiment, five artificial conversational entities (ACEs) competed in a series of five-minute long, unrestricted conversational tests.
The ACEs tried to pass themselves off as humans to the judges.
"During the tests, all of the ACEs managed to fool at least one of their human interrogators," a University of Reading spokesman said.
The tests took place as part of the 18th Loebner Prize for artificial intelligence.
The annual competition awards prizes for the most human-like machine of those entered.
Top machines from around the world were "whittled down" to the five taking part in Sunday's final, the university spokesman added.
The machines "speak" to humans using text-based conversation
"Where the machines were identified correctly by the human interrogators as machines, the conversational abilities of each machine was scored at 80% and 90%.
"This demonstrates how close machines are getting to reaching the milestone of communicating with us in a way in which we are comfortable.
"That eventual day will herald a new phase in our relationship with machines, bringing closer the time in which robots start to play an active role in our daily lives."
This year's winner was Elbot, despite failing the Turing Test. The programme's developers were awarded a $3,000 (£1,760) prize.