[Eeglablist] difficulties with event code summary from erplab?

[Kaare Mikkelsen]

Dear EEGLAB mailinglist:

(I am presently learning to use eeglab to analyse MMN-datasets, meaning
that my question does partly relate to the erplab extension. I hope that
this is acceptable, or that an alternative eeglab-exclusive solution
exists.)

As a step towards familiarising myself with eeglab, I am attempting to make
my way through the tutorial for spm/eeg, using eeglab/erplab. To this end I
am using the garrido dataset obtainable from
http://www.fil.ion.ucl.ac.uk/spm/data/eeg_mmn/. The data seems to load fine
into eeglab, but for some reason I am running into obstacles when reading
the event information?

after having created the event list, the summary of event codes (outputted
by erplab) is

Type 65024 appears   1 times
Type 65152 appears   1 times
Type 65216 appears 480 times

However, the eeglab window informs me that there are in fact 601 events.
this fits very well with the spm tutorial, which says that the rare
stimulus occurs 120 times (and not just 1). upon browsing the event
details, either through the generated elist.txt or using edit -> event
values, I see that there are indeed much more than 1 occurrence of code
"65152". Does anyone know what might be going wrong? clearly the events are
there, but eeglab persists in claiming that event "65152" only happens
once. An excerpt from the elist.txt looks like:

# item bepoch  ecode            label      onset          diff     dura
b_flags   a_flags  enable    bin

1     0       65024              ""      0.8906      0.00    0.0
 00000000     00000000   1 [       ]
2     0       65152            rare      3.0898   2199.22    0.0
 00000000     00000000   1 [      1]
3     0       65152            rare      4.5898   1500.00    0.0
 00000000     00000000   1 [      1]
4     0       65216            freq      6.0898   1500.00    0.0
 00000000     00000000   1 [      2]
5     0       65152            rare      7.5898   1500.00    0.0
 00000000     00000000   1 [      1]
6     0       65152            rare      9.0898   1500.00    0.0
 00000000     00000000   1 [      1]
7     0       65152            rare     10.5898   1500.00    0.0
 00000000     00000000   1 [      1]
8     0       65152            rare     12.0898   1500.00    0.0
 00000000     00000000   1 [      1]

(the labels are my doing, using the advanced "create eventlist" interface)

I hope someone can help clear this up.

Best regards
Kaare Mikkelsen

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Kaare Mikkelsen, Dr. Phys.
Department of Engineering
Aarhus University
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