Sorry, I should have been more clear. The OP asked whether there was a way to determine what is in the public consciousness.

There are many ways. Among the most popular these days are web and mobile analytics.

I did some consulting on a data visualization tool that was employed by one of the world's largest corporations to determine what the public had to say about its products. In that individual, specific case while I felt uncomfortable accepting the work I don't regard it as outright evil.

However I do regard it as evil for a political party to do the exact same thing.

What I learned about the way analytics are used led to my ardent effort to convince others to blackhole analytics servers. It's also the reason I don't list any of my favorite books or movies in my Facebook profile.