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Eun-Jung, It seems that you only have 2 conditions -- target condition and control condition and baseline. You should model each condition as a vector of onsets, not as a value for each scan. Thus, the duration would only be a vector of N, where N is the number of trials, rather than a series of 0s and trial duration. The baselines, which I assume is when the subject is not doing anything, should be treated as the implicit baseline. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Postdoctoral Research Fellow, GRECC, Bedford VA Website: http://www.martinos.org/~mclaren Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Thu, Feb 27, 2014 at 12:25 AM, Eunjung Choi <[log in to unmask]> wrote: > Dear experts > > Hello, I am a graduate student and a beginner of SPM. > > Here I am writing to ask a question of how to control the effect of > reaction times between two experimental conditions in 1st level analysis. > > Each subject saw target pictures and pressed a button in target condition, > and saw contol pictures and pressed a button in control condition. > > For exploring the effect of two experimental conditions, I modeled all > images into target condition, target baseline, control > condition, and contol baseline. > > If there were no problems with reaction time between two experimental > condition, T contrasts would be '[ 1 -1 -1 1]' for the effect of target > condition, and '[ -1 1 1 -1]' for the effect of contol condition. > > My questions are > > 1) How should I input the reaction times matching all time series images > in each subject data. I just tried to make one regressor and input each > reaction time matching time series data like below. When the subject just > saw the pictures, the input value was 0. When the subject pressed a button, > the real time values were inputed. Is it right? @.@;; > > [image: 본문 이미지 1] > > > > > > 2) How should I input contrasts for contolloing the effect of the reaction > times in exploring the experimental conditions compared to baseline? > > Sorry for asking such basic questions, I sincerely hope it will not bother > too much! > > Please give me any kind of advices. > > Thank everyone for your time to read! > > Regards, > > Eun-Jung Choi >