5. Modeling it as a block design *will* get you results indicating the effect of grip; however, it is the effect of grip over your block, and not a single grip. I don't see how it is possible to get the results you want with the data you have. But again, others may have some ideas.
6. I haven't used parametric modulation before, but I don't think you can in this setting.
In the future, if you're interested in the effect of individual trials, and you would like to account for percent of maximal grip, then you should increase the ISI and include a jitter. Experimental design is tricky, and there are a lot of constraints to consider, especially in fMRI research.
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From: As T.N [[log in to unmask]]
Sent: Saturday, April 27, 2013 1:54 PM
To: [log in to unmask]; Watson, Christopher
Cc: As T.N
Subject: Re: Investigating the effects of Parameters
Thanks,
I am really more interested in finding answers, or understanding, the parametric modulations and how SPM deals with it. Your point is absolutely right and I understand it. However, I have this data right now and I am trying to, as much as I can, accurately model it since it is my first fMRI analysis !
So another more two questions that I have and realized from your answer are :
5) if I model it as a block design I would not get what I want in terms of seeing the effects of the grip since the parameter should have the same length as the condition.
6) What is the best way to model it using the parameter modulation?
And of course plus my previous questions as they are really important for me to understand.
Thanks
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