Another key aspect is that temporal information provided here by the ERP measures also enables the dissociation of processes related to cue evaluation from the preparatory processes it triggers. Specifically, our data indicates that early cue evaluation is particularly sensitive to possible reward availability, whereas cued task demands do not play a major role until late in the actual task-preparation process as the target is about to occur. Furthermore, the finding that the late CNV amplitude, which has been consistently linked to task preparation, was maximal for high-difficulty reward trials, speaks to an additional critical issue. Specifically, as alluded to in the introduction, neuroeconomic experiments usually conceptualize high task demands as costs that get discounted (e.g., Croxson et al., 2009; McGuire and Botvinick, 2010). This should even more so be the case in the present experiment, as reward probability was lower in high-difficulty than low-difficulty trials. Even in this situation, we found the largest CNV amplitude in high-difficulty reward trials. If this had been merely an effect of expected reward value, the low-difficulty reward trials should have triggered the largest
