Figure 2.

A presents the signal change (mean ± standard error) for each group for both the easy‐choice condition and the hard‐choice condition, both relative to the no‐choice trials. Among control subjects, very little signal change is present in the easy‐choice condition relative to what is observed in the hard‐choice condition. For MA abusers, however, similar signal change was observed in both conditions. B directly presents the differences between the hard‐choice and easy‐choice conditions, highlighting the group effect. Although the effect was only significant in two clusters, the tendency for signal change in these two conditions to be more different among control participants than among MA participants appears to be uniform across the six clusters.