But Google is fighting back with its own smart assistant, , which was announced at the company's annual I/O developer conference on Wednesday.

"Breaking down Siri's reliance further, Google provides 100 per cent of navigation results, 61 per cent of information results, 48 per cent of commerce results and 42 per cent of local results," wrote Munster. "Among other result aggregators, Yelp provided the most local results (51 per cent) and commerce results (51 per cent), while WolframAlpha provided 34 per cent of information results."

With the release of iOS 6, Apple's new maps service will provide all of the navigation results, Yahoo Sports will be added for sports information, Open Table will provide detail about restaurants, Rotten Tomatoes will give movie show times and Fandango will allow ticket purchases. How these changes will affect Siri's accuracy is not yet known.

Munster highlighted several types of mistakes made by Siri in his test, the most common error being a response with the answer to the previous query.

When asked where Elvis was buried, Siri said "I can't answer that for you," mistaking 'Elvis buried' for the name of a person.