[Eeglablist] components direction in CNT and EEGLAB

[Arnaud Delorme]

Yes, this is the YDIR parameter of icadefs.m. Most of the EEGLAB functions will take it into account but some will ignore it and always plot the positive polarity up (this is the case for all the newer STUDY functions). If there is a strong consensus, we could make sure that this is more consistent across functions.

Arno

On Jul 13, 2012, at 3:17 PM, Scott Makeig wrote:

> I believe there is a switch you can set in your local copy of 'icadefs.m' that defines the plotting polarity in EEGLAB functions - correct, Arno?
> 
> Scott
> 
> On Fri, Jul 13, 2012 at 5:28 AM, Ruud Kalis <rkalis at ant-neuro.com> wrote:
> Dear Malahat,
> 
> The default setting in the ASA software is with negative polarity up. There is a possibility to switch between negative and positive up. Since this does not concern EEGLAB, I will send you a separate email with instructions how to perform this.
> 
> Best regards,
> Ruud
> 
> ----- Original Message -----
> From: "Arnaud Delorme" <arno at ucsd.edu>
> To: "malahat akbarfahimi" <malahatfahimi at gmail.com>
> Cc: eeglablist at sccn.ucsd.edu
> Sent: Friday, 13 July, 2012 6:52:10 AM
> Subject: Re: [Eeglablist] components direction in CNT and EEGLAB
> 
> Dear Malahat,
> 
> some researchers like to visualize ERP with negative polarity up. You can do it as well in EEGLAB but this is not the default. I think this is where you confusion comes from. There has been heated debates as to wether this old convention (negative going up) should be kept. It is tending to disappear slowly.
> 
> Best regards,
> 
> Arno
> 
> On Jun 28, 2012, at 2:06 AM, malahat akbarfahimi wrote:
> 
> > Hi,
> > I am working on face perception with ERP. My EEG records were by ANT and I sure the direction of P300 in down , but after we processing these signals with EEGLAB is it possible the direction were changed, is it possible that  in EEGLAB  codes  that changed the direction of ANT or CNT files as a standard forms (ex P300 showed in up direction)?  I really confused and check all possible events but the cons and pons are equal.appreciate any help.
> > thanks
> > --
> > Malahat Akbarfahimi
> > Occupational Therapist-PhD Student of cognitive neuroscience
> > Faculty Member
> > Occupational Therapy Department-Rehabilitation Faculty
> > Tehran University of Medical Science
> > Iran-Tehran
> >
> >
> >
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> --
> Ruud Kalis
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> -- 
> Scott Makeig, Research Scientist and Director, Swartz Center for Computational Neuroscience, Institute for Neural Computation; Prof. of Neurosciences (Adj.), University of California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott

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