using a t-contrast with +1 will show positve correlations only - a negative t-contrast (-1) will show the negative correlations and a F-contrast (1 or -1 doesn't matter) will show both
> Dear Sir or Madame,
> For several weeks I am trying to find the solution for the following
> problem. After functional connectivity analysis I made a factorial
> design to look at the results. I am trying to find out how I can see
> whether the results are positive or negatively correlated with my
> seed voxel. SPM5 only shows positive t-values. Even when I make a
> plot with my effect of interest I only see positive values. Does
> this mean that I only found positive correlations? Is this the right
> way to check whether the results I found are positive or negatively
> correlated with my seed voxel?
> I really hope you can help me.
> I hope to hear from you soon.
> Yours faithfully,