[Eeglablist] Simple intro to ERSP

Kremlacek, Jan jan.kremlacek at lfhk.cuni.cz
Tue Jul 6 07:07:19 PDT 2010

Dear Dorothy,

thank you for a nice tutorial. I would like to make a note to a problem
of the ERSP of  difference vs. difference of ERSPs. 

In your example you are using a fixed phase, which advances the first
approach (the ERSP of difference) as you showed, but in a case that the
induced activity is not phase aligned, then the second approach
(difference of ERSPs) should bring you more sensitive results.

With kind regards,

-----Original Message-----
From: eeglablist-bounces at sccn.ucsd.edu
[mailto:eeglablist-bounces at sccn.ucsd.edu] On Behalf Of Dorothy Bishop
Sent: Saturday, July 03, 2010 10:54 AM
To: eeglablist at sccn.ucsd.edu
Subject: [Eeglablist] Simple intro to ERSP

To try and ensure I understand time-frequency analysis, I am writing a
simplified introduction that assumes little background knowledge.
I have adopted the approach of using simplified simulated signals to
allow users to explore what happens with different command parameters.
A draft, just covering aspects of ERSP can be found on

I hope it might be useful to others, but it is a case of the blind
leading the blind, and there may be errors in it.
Comments and corrections would be very welcome - I'd be especially
grateful if someone knowledgeable would look at it and let me know if
I've got things wrong.

One reason I did this was because I wanted to compare results on ERSP in
a mismatch paradigm when you
a) subtracted condition 1 from condition 2 and then did ERSP on the
difference waveform
b) Did ERSP on condition 1 and condition 2, and subtracted the resulting

My simulations suggest (a) is more sensitive, but I'd be interested in
other views on this.

Dorothy Bishop
Professor of Developmental Neuropsychology
Department of Experimental Psychology
University of Oxford
Website: http://psyweb.psy.ox.ac.uk/oscci/
Blog: http://deevybee.blogspot.com/
tel: +44 (0)1865 271369
fax: +44 (0)1865 281255

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