If you're happy and you know it show your advertiser
There are a few companies out there trying to add to the already significant amount of data in programmatic buying.
Some of those advertisers are trying to find ways to better measure engagement or viewability using biometrics. However, the latest is AOL's Be On, which "utilizes users' own webcams to read their facial expressions while watching a brand's video content in order to understand what their unconscious feelings are while exposed to the brand's messages."
The purpose of course is to judge people's emotional reactions to brand messages and then improve the user experience based on this. It is currently in opt-in only mode but AOL is looking to apply this to their wider user base.