Dear expertsHello, 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? @.@;;
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