Well, for example, "traditionally" the Stroop interference effect refers to
the relatively slower response latencies reported for the incongruent
colour-naming condition. If you don't see it, should you still analyse your
imaging data on the presumption that imaging is a more sensitive indicator ?
I think the cognitive psychologists have some concerns about the methodology
of neuroimaging (e.g., Bub's article in Cognitive Neuropsychology last
year). I would agree re the relative sensitivity of the measures if it
could be proved... Personally, I think these measures/approaches are
mutually dependent.
Regards,
Greig
> From: Russ Poldrack <[log in to unmask]>
> Date: Thu, 31 May 2001 07:06:10 -0400
> To: Greig de Zubicaray <[log in to unmask]>
> Subject: Re: A thorny question re analysing fMRI data in the absence of
>
> when you say that the process hasn't been established in the traditional
> sense,
> what exactly do you mean?
>
> it's interesting that some cognitive psychologists seem to view imaging as
> basically a really expensive RT. What strikes me (having spent several years
> of my
> life running RT studies) and what spurred my previous response is the
> intuitive
> sense that imaging data are at least in some cases MUCH less noisy than RT
> data. I
> would feel lucky if 2/3 of my individual subjects showed a particular RT
> effect
> (even if it was highly significant in the anova), whereas I regularly see
> imaging
> effects where every subject shows the effect.
>
> cheers
> russ
>
> Greig de Zubicaray wrote:
>
>> Thanks Joe and Russ for these thoughtful replies,
>>
>> I posed the question because there is a chronometric tradition within
>> experimental/cognitive psychology that might disagree with the relatively
>> stronger inference being ascribed to neuroimaging data here (some of my
>> cognitivist colleagues have already taken me to task about this), given that
>> the presence of a cognitive process of interest hasn't been established in
>> the traditional sense.
>>
>> Regards,
>>
>> Greig
>>
>> on 31/05/01 5:54 PM, Joseph T. Devlin at [log in to unmask] wrote:
>>
>>> I agree with Russ -- the imaging could well be sensitive to effects not seen
>>> in RT data. I think the many studies which have demonstrated "implicit"
>>> neural processing are good examples of this. This extra sensitivity comes
>>> from the fact that RT (or error data) is a very indirect measure of the
>>> underlying neural/cognitive processes because it provides a single score for
>>> a
>>> combination of processes. rCBF or BOLD are also indirect measures of neural
>>> activity but you get many thousands of measures and each is more closely
>>> related
>>> to regional neural activity than any behavioural measure. Consequently your
>>> imaging analysis may be more sensitive to "implicit" processes, which in
>>> many
>>> cases are interesting/revealing.
>>>
>>> - Joe
>
> --
> Russell A. Poldrack, Ph. D.
> MGH-NMR Center
> Building 149, 13th St.
> Charlestown, MA 02129
>
> Phone: 617-726-4060
> FAX: 617-726-7422
> Email: [log in to unmask]
> Web Page: http://www.nmr.mgh.harvard.edu/~poldrack
>
>
--
Dr Greig de Zubicaray
Centre for Magnetic Resonance
The University of Queensland
Brisbane, QLD 4072
AUSTRALIA
Tel: +61 (0) 7 3365 4250 [direct]
+61 (0) 7 3365 4100 [CMR]
Fax: +61 (0) 7 3365 3833
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