Errors in the NoGo version of the task.

<p>In the NoGo version of the task, erroneous reactions to target signals were executed responses (commission errors). The average rate of target commission errors is displayed per group over blocks of 40 presentations over the 120 presentations during conditioning (blocks 1 to 3, labelled C1, C2 and C3) and the subsequent 40 presentations during deconditioning (block 4, labelled D). The error bars indicate the standard error of the mean. Note the significant increase of commission errors during deconditioning compared to any of the conditioning blocks in healthy subjects and patients with Parkinson's disease off levodopa (indicated by asterisks), whereas in patients on levodopa this effect could not be detected.