Google's artificial intelligence technology has a considerably higher I.Q. than Apple's Siri virtual assistant, according to a new academic paper attempting to compare the smarts of various artificial intelligence systems.

The paper — written by a trio of Chinese researchers, including Yong Shi, executive deputy director of the Chinese Academy of Sciences' Research Center on Fictitious Economy and Data Science — says that in 2016 Google's AI had an IQ of 47.28. It came out ahead of Chinese search engine Baidu (32.92) and Microsoft's Bing (31.98) and had almost double the IQ of Siri (23.94).

Notably, none of these systems had a higher IQ than a 6-year-old (55.5), much less an 18-year-old (97), the researchers found.

But the Google and Microsoft systems have been getting smarter. In 2014 Google's IQ score was 26.5, while Microsoft's was 13.5. At that time the researchers were not yet analyzing Baidu and Siri.

Apple, Google and Microsoft have all been , which can yield improvements in speech recognition, image recognition and other areas. These techniques can be applied to revenue-generating processes like serving ads.

But comparing companies' existing AI systems — and seeing how they stack up with human beings — has been difficult, and that's one reason the researchers have attempted to create a comparison method. The researchers have taken into consideration the systems' abilities around "knowledge mastery, learning, use and creation."

The new paper, published on Sunday, does touch on , the system for playing the Chinese board game of Go from Google parent company Alphabet's DeepMind group. While the researchers didn't give it an IQ score, they did conclude that its intelligence is below that of humans.

Google declined to comment. Apple was not immediately available to comment on the study.