WARNING: Some SSI survey "invitations" read something like this:

You'll notice there is no incentive amount mentioned, nor is there a "participation" amount offered for trying but being disqualified. It does not appear this is an oversight!

The survey is called a "PopRewards" survey and (after the qualification questions) asks a lot of questions about your recent TV viewing, including what went on in the programs and the commercials (takes much more than 5 minutes, by the way). After the survey is over and you're congratulated for successfully completing the survey, there is nothing added to your total -- even days later. There is apparently no reward for taking the survey! (Well, they didn't promise any, did they?)