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Dear Avantika, even if absolute movement is small, any kind of stimulus related movement (i.e. related to button press, movement of visual stimuli) will be difficult to handle. This can't be checked by looking at absolute movement only. If you didn't do so already, you should include your realignment parameters as additional regressors in your first level models. This should explain away most of the variance related to head motion. In the case of stimulus related motion it may also remove stimulus related variance, since it is difficult to distinguish between these two sources of variance. Hope this helps a little, Volkmar