Dear SPM experts,
I am designing a reaction time study to contrast patients' BOLD with healthy
adults'.
The current plan it to set a move epoch of 45 sec alternating with a rest
epoch of 15 sec.
Each move epoch will have "fast-as-can" repeated trials.
Since the majority of patients are expected to move slower than the healthy
adults, this "fixed epoch duration" design will end up with more trials in healthy
than patients within a 45 sec epoch.
To control for the number of repetitions within an epoch, we are planning on
allowing each subject to move for the same number of repetitions within each
move epoch. However, patients will have longer epoch compared to healthy
adults (since they are slower and the goal of task is to press the key as fast
as possible).
I am wondering if SPM will handle a blocked design analysis for epochs with
variable lengths?
Will the discrepancy in epoch lengths between patients and healthy adults
give me troubles in terms of first level or second level analysis? Do I need to
have the same onset time (for each moving epoch) across different
participants in order to run a group analysis?
Any comments are well-appreciated.
Thank you!
Janice
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