https://services.google.com/inquiry/user_study
Quote:
Do I get paid?
Yes – it depends on the type of study, but typically we pay $75 for each hour that you spend with a Google researcher, either in person or on the phone. Most studies last for one to one-and-a-half hours. We don't pay for your travel time, or travel expenses, though. For online surveys, which you complete from your own computer, the amount varies, depending on the length of the survey.