[Eeglablist] Removal of distortion due to overlapping ERP responses - ADJAR filter

Frank H Duffy fhd at sover.net
Wed Aug 4 08:23:57 PDT 2010

A key thing is to understand whether, on physiological grounds, there 
may be an interaction between the two conditions, i.e., A alters the B 
waveform (or the opposite)  as seen for the long latency AER if you 
closely pair auditory clicks.  Is the problem a simple arithmetic 
(result =A+B)  or is there likely to be a strong interaction effect 
between A and B?  Indeed some people estimate the degree of interaction 
by adding A alone and B alone signals  and compare to the A+B experiment.
Good luck.

Frank  fhd at sover.net

On 8/2/2010 1:38 PM, Niko Busch wrote:
> Hi everyone,
> I am looking for a way to remove the distortion from an ERP waveformthat is due to overlapping ERP responses to different events. I willemploy an experimental paradigm in which an experimental event A isfollowed by an event B after a variable SOA on each trial. My interestis in the ERP evoked by the Bs. However, the resulting ERP waveform -time-locked to event B - will be "contaminated" by the responses to theAs.
> It seems that people use two different approaches to remove the contribution of the As:
> 1. Include trials with A events only and then subtract the average of A from the average of A+B.
> 2. A convolution approach - the ADJAR method specified in this paper:
> Woldorff MG. Distortion of ERP averages due to overlap from temporallyadjacent ERPs: analysis and correction. Psychophysiology. 1993Jan;30(1):98-119.
> Has anyone implemented ADJAR or something similar in Eeglab/Matlab andis willing to share the code? Any help would be very much appreciated!
> Best,
> Niko
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