Performance differences in reaction tasks are reflected in event-related brain potentials (ERPs)

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Abstract
Event-related potentials (ERPs), which can be extracted from the electroencephalogram (EEG), are assumed to reflect distinct cognitive processes in real time. Hence ERP analysis could be used in cognitive ergonomics as a tool to specify, for example, bottlenecks or sources of individual performance differences. Such specific results may be helpful to change the tasks or train the subjects specifically. In the present exploratory study, the authors investigated whether subjects with large spontaneous differences in performance accuracy, as defined by their error rates in a speeded binary choice reaction task, also differ in the structure of their ERPs. The ten subjects were divided post hoc into two groups with relatively low (about 6%) and high (about 20%) error rates. While the reaction times were not significantly different for both groups, the ERPs revealed clear group differences. First, large differences were seen in the late part of the contingent negative variation (late CNV), which is assumed to reflect preparatory processes. Subjects with few errors ('GOOD') had a large late CNV, while subjects with many errors ('POOR') showed virtually no late CNV. Second, the late P300-subcomponent (which is related to response identification) was smaller and delayed for POOR compared to GOOD subjects. Finally, the ERP shows signs of poor movement control in POOR subjects. The high error rate of POOR subjects can hence be explained by: (1) their insufficient preparation for the next trial (small late CNV), which impaired response identification (small and delayed late P300 subcomponent); and (2) their poor movement control. These interpretations have to be regarded as preliminary and should be validated with larger groups of subjects. In conclusion, the main reasons for the profound performance differences between the groups, namely differential preparation and movement control, could be elucidated by ERP analysis. A potential ergonomics application of these results is that they suggest specific strategies (for example, a preparation and motor control training) to improve the performance of POOR subjects in comparable work conditions.