A Sony patent has revealed details for a sensor that measures the changing chemical make-up of your saliva.
The documents were published today via the US Patent Office but were filed back in October 2012 by Dr. Ozlem Kalinli-Akbacak, a research engineer at SCEA.
"Emotion recognition or understanding the mood of the user is important and beneficial for many applications; including games, man-machine interface etc.," the patent states. "Emotion recognition is a challenging task due to the nature of the complexity of human emotion; hence automatic emotion recognition accuracy is very low."
This new system would use a suite of sensors all over a user's body - such as a finger-based ring that could detect your heart rate, blood pressure and respiration (similar to Nintendo's abandoned Wii Vitality Sensor concept).
A head-based sensor "band/cap" would measure brain activity and stimulation, while another part of the patent mentions sensors embedded within a PlayStation controller - an idea Sony is rumoured to have explored and then ditched for the final PS4 pad.
All of this data would then be transmitted to a "computer system" to gauge a user's physical reactions.
Despite today's publication it's unclear whether Sony still intends to do anything with the idea. The project doesn't appear to be connected to the company's newly-announced Project Morpheus VR tech, however.
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