To manipulate the two experimental factors of interest – voluntary response selection and performance monitoring – four versions of the task were run which differed only in what people were required to do immediately after the presentation of a switch cue (Figure 2b). In two of the conditions (GENERATE+MONITOR and GENERATE), on the first trial after presentation of the switch cue, participants voluntarily chose what action to select, opting to respond using one of the two stimulus-response mappings that differed from the previous response rule set. In the two other conditions (FIXED+MONITOR and CONTROL), participants never had to choose for themselves what to do after a switch cue but instead were told by the experimenter before the experiment began which response to make on that first trial. When performing either of the MONITOR conditions, immediately after the switch cue, participants were initially uncertain which rule set was now in place and so had to pay attention to the feedback information to guide subsequent behaviour. This differs from previous studies which have manipulated the choice demands (O'Doherty, Critchley, Deichmann and Dolan,
