Hi Dr. Smith
Thanks so much for your response. My scenario is a little simpler than
the one you described. I have the following 3-column format text file
as my only EV:
0 25 1
120 25 0
150 25 1
260 25 0
300 25 1
410 25 0
440 25 1
I am trying to model my experimental condition (1) as only 25 seconds
and my baseline/control (0) as only 25 seconds. Will my baseline also
include the un-modeled times? Does this mean I should add a second EV
that includes the un-modeled times?
Thanks very much again for your time.
Arne
On Mar 29, 2007, at 6:23 AM, Steve Smith wrote:
> Hi,
>
> On 29 Mar 2007, at 04:42, Arne Ekstrom wrote:
>
>> Hello
>>
>> I have a quick clarification question about 3 column format in FEAT:
>>
>> If I define my experimental and control durations with specific
>> values in column 2 of my text file, will FEAT use *only* these values
>> for contrasting my experimental condition against my control
>> condition? Or is that only true for the experimental condition? In
>> other words, the experimental condition (defined with 1s) will be of
>> the duration set in column 2 while baseline will be everything else
>> (including periods outside of what is defined in column 2 for the
>> control condition)?
>>
>> I know this question may sound silly, but it appears from the output
>> of the stats console in FEAT that the baseline condition consists of
>> everything other than durations defined by your experimental
>> condition (using three-column format) and is *not* restricted to
>> periods you define as control periods in your second column. Or
>> perhaps I am confused?
>
> I'm not sure exactly what you're asking, but I think you're saying
> that you in effect have 3 different conditions:
> 1 baseline
> 2 control events
> 3 experimental events
>
> You are not explicitly modelling (1) as a separate EV, but are
> specifying (2) and (3) as separate EVs, each with their own 2-column
> custom timing files. Anything outside the duration of (2) or (3)
> events is assumed to be baseline.
>
> Hope this helps, Steve.
>
>
>
>>
>> Any help is greatly appreciated. Thank you very much for your time
>> in advance.
>>
>> Arne
>>
>> Arne Ekstrom, Ph.D.
>> Postdoctoral Fellow
>> Center For Cognitive Neuroscience, Semel Institute
>> University of California, Los Angeles
>> ph: 310.794.9360
>> fax: 310.794.7406
>> http://airto.hosted.ats.ucla.edu/~aekstrom/
>
>
> -----------------------------------------------------------------------
> ----
> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
> -----------------------------------------------------------------------
> ----
>
>
Arne Ekstrom, Ph.D.
Postdoctoral Fellow
Center For Cognitive Neuroscience, Semel Institute
University of California, Los Angeles
ph: 310.794.9360
fax: 310.794.7406
http://airto.hosted.ats.ucla.edu/~aekstrom/
