Dear SPMers,

We performed an experiment on readers and pre-readers with speech and print conditions. On second level analysis we computed null conjunction for the 2 contrast in each group (one sample t-test) which produced significant activation in readers while not in pre-readers. However, when the paper was sent to review one of the reviewers wanted us “to compute the conjunction of print and speech on the first level and put these contrasts into a 2-sample t-test on the second-level”.

However we came across some difficulties. If we save thresholded SPM map from each subject when performing null conjunction in SPM contrast manager and feed these maps to 2nd level the model cannot be estimated and there is an error saying “there are no inmask voxels” (even though we used very lenient p<0.05 uncorrected threshold for the 1st level conjunction). Is there a better way of doing multisubject conjunction?

Thank you in advance,

Marek




-- 
Marek Wypych PhD
Laboratory of Brain Imaging (LOBI)
Neurobiology Center
Nencki Institute of Experimental Biology
Pasteur 3, 02-093 Warsaw, Poland
Tel.: +48 22 5892 550
http://lobi.nencki.gov.pl/