```Hi Claus & SPMers - thanks for pointing that out. You were correct.

After fixing this I realized that there are a couple of mistakes in the  "README_GLM_PPI.txt" http://www.fil.ion.ucl.ac.uk/~wpenny/datasets/attention/README_GLM_PPI.txt
for the practice dataset. For example, I believe that there are
actually 4 conditions, but it is written as though there are only three (see examples below)

Specifically, here are the other problems that I found with the "README_GLM_PPI.txt"

The text instructs you to specify the contrast [0 0 -1 1 0]. There are two things wrong with this, one, this is the problematic contrast that prompted this message. Two, you cannot specify 5 contrast codes for an SPM that only has 4 conditions. Experienced users know this, but as it is a practice data set I bet this trips people up.The second set of contrast does basically the same thing: [-2 0 1 1 0]And finally the point listed above, that there are four conditions but the instructions repeat "condition 3" twice making it quite confusing.
Thanks again!

ORIGINAL TEXT - http://www.fil.ion.ucl.ac.uk/~wpenny/datasets/attention/README_GLM_PPI.txt11. Number of conditions [4]
12. Name for condition 1 [Fixation]
13. vector of onsets - Fixation [fix_index]
13. duration[s] (events=0) [0]
14. Parametric modulation [None]
15. Name for condition 2 [Stationary]
16. vector of onsets - Stationary [stat_index]
17. duration[s] (events=0) [0]
18. Parametric modulation [None]
19. Name for condition 3 [NoAttMot]
20. vector of onsets - NoAttMot [natt_index]
21. duration[s] (events=0) [0]
22. Parametric modulation [None]
23. Name for condition 3 [AttMot]
24. vector of onsets - AttMot [att_index]
25. duration[s] (events=0) [0]
26. Parametric modulation [None]
27.
User specified [0]

MODIFIED TEXT

12. Name for condition 1 [Fixation]
13. vector of onsets - Fixation [fix_index]
13. duration[s] (events=0) [0]
14. Parametric modulation [None]

15. Name for condition 2 [Stationary]
16. vector of onsets - Stationary [stat_index]
17. duration[s] (events=0) [0]
18. Parametric modulation [None]

19. Name for condition 3 [NoAttMot]
20. vector of onsets - NoAttMot [natt_index]
21. duration[s] (events=0) [0]
22. Parametric modulation [None]

23. Name for condition 4 [AttMot]
24. vector of onsets - AttMot [att_index]
25. duration[s] (events=0) [0]
26. Parametric modulation [None]
27. User specified [0]

----- Original Message ----
Sent: Thursday, February 21, 2008 4:34:28 PM
Subject: Re: [SPM] Nonsensical results from sample SPM5 data set. What are we doing wrong?

contrast
looks
wrong
-
seems
like
you
are
comparing
the
constant
(+1,
last
column)
against
the
3rd
column
(-1)
You
probably
should
use
something
like
a
[1
0
0
0]
to
assess
the
PPI

Hth
C

************
Dr.
Claus
Lamm
Research
Associate

Social
Cognitive
Neuroscience
Department
of
Psychology
The
University
of
Chicago

5848
S.
University
Avenue,
Chicago,
IL
60637
Phone:
(773)
702-4661
Fax:
(773)
702-0886

EMail:
Web:
http://scnl.org/claus.html

-----Original
Message-----
From:
SPM
(Statistical
Parametric
Mapping)
On
Behalf
Of
Shaquanda
Jones
Sent:
Thursday,
February
21,
2008
3:25
PM
To:
Subject:
[SPM]
Nonsensical
results
from
sample
SPM5
data
set.
What
are
we
doing
wrong?

Dear
SPMers,

We
have
been
playing
around
with
the
sample
SPM
data
set
available
here
(attention
to
visual
motion):

http://www.fil.ion.ucl.ac.uk/~wpenny/datasets/attention.html

We
have
analyzed
the
results
using
the
directions
listed
in
the
data
set
(using
the
updated
SPM5),
but
as
you
can
see
by
the
screen
shot,
we
are
obviously
getting
results
that
do
not
make
sense
(i.e.
t
values
in
the
hundreds).
We
are
probably
doing
some
thing
simple
wrong,
but
it
is
not
obvious
to
us
yet
what
that
is.
Any
suggestions
would
be
much
appreciated.

Sincerely,

Nonsensical
results
from
sample
SPM5
data
set.
What
are
we
doing
wrong?

____________________________________________________________________________
________
Be
a
better
friend,
newshound,
and
know-it-all
with
Yahoo!
Mobile.
Try
it
now.
http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

____________________________________________________________________________________
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```