Dear all,
Thank you for providing this service. I am analyzing a very simple motor tapping paradigm presented in block design with a TR of 3 seconds. The onset times I entered for the start of the task blocks using the 1st level stats GUI are scans 9, 25, 41, 57 (duration = 8 scans). Unfortunately, the design matrix seems not to reflect those onset times, indicating that task blocks are starting at scans 12, 28, 44, and 61, suggesting a shift of 3 scans. As a result, they are also misaligned to the regressors in the adjacent columns. My first thought was that the design matrix was capturing the delay of the HRF; however, that delay would only be a few seconds, not 3 scans (= ~9 seconds). Is it somehow possible that my onset times are being offset by 3 or so scans, or is it more likely that the design matrix is not displaying correctly for some unrelated reason?
Thank you!
Ted
|