I aim at finding relative differences in SCR among three types of unconditioned events (reward, punishment, no monetary change). Each unconditioned event is anticipated by a different flash of colour (blue, pink, yellow). Via classical conditioning, these flashes should become conditioned stimuli and I aim at finding relative differences in SCR among them.
I am using brief stimuli (duration < 1s).
At the moment I have set up a GLM and I have a question regarding SCR latency: is it best practice to leave it fixed or is it a good idea to let it vary?
I am working via matlabbatch scripting and at the moment I have
matlabbatch_glm_1st_lev{1}.pspm{1}.first_level{1}.scr{1}.glm_scr.latency.fixed = 'fixed';
Could you provide a matlabbatch example where latency is 'free'?
Many thanks and best,
Ambra
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the 'free' option for latency is supposed to work with startle eye blink data. The algorithm behind it does not work very well with SCR data when the ITIs are such that SCRs overlap (ie. ITI shorter than at least 30 s).
Instead, varying SCR latency is better accounted for by using the time derivative of the SCRF, and reconstructing the response. This is the default option in PsPM, and evaluated in Bach et al. 2013 Psychophysiology.
For brief stimuli, I would have thought that DCM is not going to give you more information.
Hope this helps
Dominik
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Hello,
I aim at finding relative differences in SCR among three types of unconditioned events (reward, punishment, no monetary change). Each unconditioned event is anticipated by a different flash of colour (blue, pink, yellow). Via classical conditioning, these flashes should become conditioned stimuli and I aim at finding relative differences in SCR among them.
I am using brief stimuli (duration < 1s).
At the moment I have set up a GLM and I have a question regarding SCR latency: is it best practice to leave it fixed or is it a good idea to let it vary?
I am working via matlabbatch scripting and at the moment I have
matlabbatch_glm_1st_lev{1}.pspm{1}.first_level{1}.scr{1}.glm_scr.latency.fixed = 'fixed';
Could you provide a matlabbatch example where latency is 'free'?
Many thanks and best,
Ambra
Second question: instead of GLM, would msybe DCM better fit my needs?
Thanks and best,
Ambra
Hi Ambra
the 'free' option for latency is supposed to work with startle eye blink data. The algorithm behind it does not work very well with SCR data when the ITIs are such that SCRs overlap (ie. ITI shorter than at least 30 s).
Instead, varying SCR latency is better accounted for by using the time derivative of the SCRF, and reconstructing the response. This is the default option in PsPM, and evaluated in Bach et al. 2013 Psychophysiology.
For brief stimuli, I would have thought that DCM is not going to give you more information.
Hope this helps
Dominik