[ffriend]

Well, I definitely do have other applications for it. For example, I know that similar software has been used in labs to estimate people's reaction to videos and game features, in mobile applications to improve interaction with a user, etc.

My interest to offline applications comes from personal experience: recently we demonstrated our product (not emotion recognition, but also capturing user's face) on an exposition. People came to our stand, used the product (so they clearly opted-in), asked questions, etc. After 2 days, we asked a girl at the stand "What do people think about the product"? "Well, in general, they are interested" she answered. Not much info, right? Definitely less informative than "65% expressed mild interest, 20% had no reaction and 5% found it disgusting, especially this feature".

So I don't try to justify this use case - my life doesn't depend on it - but I find it stupid not to try to understand your clients better when it doesn't introduce a moral conflict.