I have an experiment with two groups (treatment, placebo), each with pre and post sessions for 3 conditions. How can I compare across groups and across conditions? I can't seem to figure out how the second level results screen is setup for the statistics. So I have two questions:

1) If I wanted to perform an f-test of the treatment/placebo across pre/post, how would I set that up?
2) What does the identity (eye(n)) matrix show? How is that different than specifying [1 1]?