I have a sample of 19 people who I measure for some factor. In step 2, I give them all some information and test again for the same measure. Step 2 is repeated 5 additional more times. So, in effect they are given additional information 6 times. Thus for each person I have 7 performance measures - one without information and six additional measures with information. I want to test if the performance improves with every additional piece of information. How can this be done?