The Turing Test, proposed by Alan Turing in 1950, is considered as a basic definition of Artificial Intelligence. It was used to see if something is a person or a machine. A computer passes the test if an interrogator cannot tell whether the answers come from a person or a computer. To pass a rigorously applied test, computer need to have certain capabilities like Natural Language Processing, Knowledge Representation, Automated Reasoning and Machine Learning.
But a recent study shows that the Turing Test has some limitations. Co-author Kevin Warwick, a computer scientist at Coventry University in England said that the Turing Test will not work in the case where the person or machine whoever is being interrogated chooses to stay silent. Read more about it at: http://www.livescience.com/55356-flaw-detected-in-turing-test.html