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Hi My experiment has no explicit task(well, that is an oxymoron!) - requires free viewing of moving images. The fMRI collected is collected TR of 2 seconds and the total duration of the experiment is around 8 minutes . At the 1st level analysis phase, I notice big variations when 'Onset'(block) is changed from 20 to 22 with a duration of 20, for example. The design is in seconds. Is this expected? For example: At an onset = 20 & duration = 20, I see not even one voxel highlighted but when the onset=22 and the duration= 22 or 25, there is huge response. Question: in an task independent/free viewing paradigm, can blocks be selected in the design? Regards Kavita