Researchers have found a way for computers to recognise 21 distinct facial expressions - even those for complex or seemingly contradictory emotions such as 'happily disgusted' or 'sadly angry'. The study by Ohio State University more than triples the number of documented facial expressions that researchers can now use for cognitive analysis. "We've gone beyond facial expressions for simple emotions like 'happy' or 'sad'. We found a strong consistency in how people move their facial muscles to

Researchers have found a way for computers to recognise 21 distinct facial expressions - even those for complex or seemingly contradictory emotions such as 'happily disgusted' or 'sadly angry'.

The study by Ohio State University more than triples the number of documented facial expressions that researchers can now use for cognitive analysis.

"We've gone beyond facial expressions for simple emotions like 'happy' or 'sad'. We found a strong consistency in how people move their facial muscles to express 21 categories of emotions," said Aleix Martinez, associate professor of electrical and computer engineering at Ohio State.

The resulting computational model will help map emotion in the brain with greater precision than ever, and perhaps even aid the diagnosis and treatment of mental conditions such as autism and post-traumatic stress disorder (PTSD).

Until now, cognitive scientists have confined their studies to six basic emotions - happy, sad, fearful, angry, surprised and disgusted - mostly because the facial expressions for them were thought to be self-evident.

But deciphering a person's brain functioning with only six categories is like painting a portrait with only primary colours, Martinez said.

The study photographed 230 volunteers - 130 female, 100 male, and mostly college students - making faces in response to verbal cues.

In the resulting 5,000 images, they tagged prominent landmarks for facial muscles, such as the corners of the mouth or the outer edge of the eyebrow.

They used a method used by psychologist Paul Ekman, the scientific consultant for the television show "Lie to Me". Ekman's Facial Action Coding System, or FACS, is a standard tool in body language analysis.

They searched the FACS data for similarities and differences in the expressions, and found 21 emotions - the six basic emotions, as well as emotions that exist as combinations of those emotions, such as "happily surprised" or "sadly angry."

The researchers referred to these combinations as "compound emotions." The model was able to determine the degree to which the basic emotions and compound emotions were characterised by a particular expression.

For example, the expression for happy is nearly universal: 99 per cent of the time, study participants expressed happiness by drawing up the cheeks and stretching the mouth in a smile.

Surprise was also easily detected: 92 per cent of the time, surprised participants opened their eyes wide and dropped their mouth open.

"Happily surprised" turned out to be a compound of the expressions for "happy" and "surprised."

About 93 per cent of the time, the participants expressed it the same way: with the wide-open eyes of surprise and the raised cheeks of happiness - and a mouth that was a hybrid of the two - both open and stretched into a smile.

Now, as CTO for Oculus VR, he says he "wasn't expecting Facebook" but thinks "they get the Big Picture".

Having left Id Software in 2013 in order to push boundaries at Oculus, Carmack wrote in response to concerns raised by digital musician Peter Berkman, one quarter of chiptune band Anamanaguchi.

Carmack contrasted the development of virtual reality tech with that of Steam, Valve's digital distribution games platform for Mac, Windows and Linux PCs.

"For years, the industry thought Valve was nuts, and they had the field to themselves. Valve deserves all their success for having the vision and perseverance to see it through to the current state," he wrote.

"VR won't be like that. The experience is too obviously powerful, and it makes converts on contact. The fairly rapid involvement of the Titans is inevitable, and the real questions were how deeply to partner, and with who," Carmack explained, casting the Oculus acquisition as a necessity.

"Honestly, I wasn't expecting Facebook (or this soon). I have zero personal background with them, and I could think of other companies that would have more obvious synergies."

"However, I do have reasons to believe that they get the Big Picture as I see it, and will be a powerful force towards making it happen. You don't make a commitment like they just did on a whim."

Berkman's objections were built around three pillars – data-mining virtual reality, the creation of an information monopoly, and the nature of good ideas.

He lamented the "most promising VR company being acquired by the world's largest data mining operation".

"Cultural evolution is the most important thing in the age of information, good ideas can and should change paradigms," he said, arguing that Oculus is getting "sucked into the old system just as [it] reach[es] potential to break a standard model."

Carmack, who is also founder of a rocketeering company, later conceded that Oculus's new owner may cause him to reevaluate his own plans.

"The FB deal probably will get me to take another swing at aerospace," he tweeted, "but not for several years. I have divided my focus too much in the past," though he didn't say whether that was for financial or ideological reasons.