Hi Catherine,

Sure, using hour_targets[3..4] would mean the sum of betas in sub-bricks 56 and 58 (assuming it is actually the sum that you want).
As a side note, it is often nice to make contrasts unit components, using averages rather than sums. This would not affect any statistics (t/F, say), but it might make the values more meaningful. For example, consider '+0.5*hour_targets[3..4]'.

Yes, the corresponding betas (zero-based indices 3, 4) for RT would be specified as hour_targets[11..12].

Yes, it looks like sub-bricks 88 and 90 would correspond to the same summed pair of the confidence modulator, hour_targets[19..20].

I know this is a little tedious. It gets so much messier when TENTs are used.


Some things to note:
1. One can verify the index list for regressors using something 1d_tool.py:

1d_tool.py -infile X.xmat.1D -show_group_labels

2. For verifying, this can be compared with text output from 3dDeconvolve, such as in sample output from AFNI_data6/FT_analysis:

GLT matrix from 'SYM: 0.5*vis +0.5*aud':
0 0 0 0 0 0 0 0 0 0 0 0 0.5 0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

3. If you would prefer a multi-line contrast (generating an F-stat) to the single line one (generating a t-stat with the contrast sum), use multiple [[]], as in: hour_targets[[11..12]]

Additional details can be found in DeconSummer2004.html .

- rick