The sessions last 90 minutes total. There is an intake form that that you fill out, ideally before you arrive for your session.
The process uses a hair-gel that you may want to wash out if you are on your way to work, etc. Otherwise, the process is harmless.
Read more and sign up.
If you're interested but not certain, curious about what sorts of "tasks" you'll be expected to do, or want more information the "EEG cap", you may want to read Vicki Brown's blog post about her experience with the brain scanning study last June!