[human-electrophysiology] Re: Any ideas about summing ERPs?
- From: "Atlanta Flitton" <a.flitton@xxxxxxxxxxxxx>
- To: human-electrophysiology@xxxxxxxxxxxxx
- Date: Mon, 6 Aug 2007 09:48:27 +0100
We are looking at the processing of spoken words and the differences when
you have visual information (ie: the face and articulatory movements AVF)
vs. when you just hear a word (the auditory condition A) or when you just
see the articulatory movements but no sound (the visual condition V). In
previous work on interaction effects they use the formula
AV = (A+V)-AV
It is to show that the change you see (in the ERP) for the audio-visual
condition is not just a summation of the two mono-stimulation conditions
(the A and the V).
I can get the Grand Averages for all conditions AV, A and V individually,
but I'm not sure how to "add" the A and V conditions. My logic tells me
that what you do is just do an average for all you're A and V ERPs, but I'm
not sure if this is the way it is done.
Or I wondered if there was a way of adding the grand averages? I don't want
a difference wave (I can do that but it is not adding, it is subtraction).
I hope this explains it a bit better, but if not let me know because it is
important that I fully understand what I'm trying to do so if I'm really bad
at explaining I will revise.
Many thanks,
Atlanta
-----Original Message-----
From: human-electrophysiology-bounce@xxxxxxxxxxxxx
[mailto:human-electrophysiology-bounce@xxxxxxxxxxxxx] On Behalf Of T Elliman
Sent: 03 August 2007 10:44
To: human-electrophysiology@xxxxxxxxxxxxx
Subject: [human-electrophysiology] Re: Any ideas about summing ERPs?
Hi Atlanta
I may be missing something, but I don't understand the formula. Could you
explain it in words?
Toby
--On 03 August 2007 10:34 +0100 Atlanta Flitton <a.flitton@xxxxxxxxxxxxx>
wrote:
>
>
> Hello all,
>
>
>
> I wondered if anyone had any experience in 'summing' ERP waves.
>
>
>
> We are using a formula AVF = (A + V) -- AVF
>
> Where:
>
> AVF = responses to Audio/visual stimuli
>
> A = responses to Audio stimuli
>
> V = responses to Visual stimuli
>
>
>
> We are hoping to see an interaction effect, but I am a little unclear
> about how to sum the ERPs. We are using Brain Vision Analyser, does
> anyone have any ideas?
>
>
>
> Many thanks,
>
>
>
> Atlanta Flitton
>
> Researcher
>
> Behavioural and Brain Sciences Unit
>
> Institute of Child Health
>
> Guilford Street
>
> London
>
> WC1N 1EH
>
>
>
>
>
>
----------------------
T Elliman
psxte@xxxxxxxxxxxxx
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