Hi,
How could I create an interaction regressor for the PPI analysis when my TR's occur not by seconds, but 1/10 of seconds? (e.g., task A occurs 12.8, 24.6, 38.9... etc).
4. Obtain the interaction regressor
First create a 1D file, AvsBcoding.1D, with 0's (at those TR's where neither condition A nor B occurred), 1's (at those TR's where condition A occurred), and -1's (at those TR's where condition B occurred). If you only consider one condition A, there are two options: (1) If the baseline condition more or less matches up with condition A, make it a constrast with condition A (coded with 1's) versus baseline (coded with -1's); (2) If you don't believe that there is modulation (interaction) between the seed and the baseline, code condition with 1's and all other time points with 0's.