[Eeglablist] ERP “scaling”

[Arnaud Delorme]

Dear Alice,

For time-frequency decomposition, there is an option in newtimef called ‘timewarp’ with additional options ‘timewarpms’ and ‘timewarpidx’.
The option calculates power in a given frequency band, then “stretches” that power in single trials. This is useful when you have two events (stimulus presentation and reaction time) and want to assess power changes, even though the difference in reaction time varies. It is an old feature, and I have not tried it in a while. Hopefully, it still works.

Stretching the data outside of this context would require more details. It is likely not meaningful to stretch the raw data in this way.

Cheers,

Arno

> On Mar 28, 2023, at 3:55 PM, Stanley A. KLEIN <sklein at berkeley.edu> wrote:
> 
> Dear Alice,
>  I think it will require more details to respond to your ERP comment.
> Your criteria didn't seem unusual to me.
> 
> Stan
> 
> On Tue, Mar 28, 2023 at 6:05 PM Alice Robert <alice.robert at unito.it> wrote:
> 
>> Hello,
>> 
>> For an ERP artifact study I am running, I need help in “scaling” ERPs in
>> order to normalize their length. For example, I would need to stretch a
>> trace that has a duration of 500 msec and an amplitude of 2 microvolts, so
>> that it fits a 750 msec window and a 3 uV amplitude.
>> I am using EEGLAB but am not good at scripting, so I am mainly using gui
>> and plugins. Any help would be greatly appreciated,
>> 
>> Thanks,
>> 
>> Alice
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