[reader_mode]

>Could you imagine the value of knowing if your heart rate went up after reading a certain message, or seeing a certain ad?

No, I'm guessing it's worth a couple of cents ?

[throwaway3699]

Perhaps. But this kind of psychographic profiling is used in labs to craft better adverts. Video games are another example.

The Left 4 Dead director was trained on player emotions and designed to improve the game, which was a huge success.

Having access to it in the field has real applications.