The Role of Task Complexity on Frontal Event-related Potentials and Evidence in Favour of the Epiphenomenal Interpretation of the Go/No-Go N2 Effect

It is well established that task complexity can affect both performance and brain processing. Event-related potentials (ERPs) studies have shown modulation of the well-known N2 and P3 components. However, limited information is available on the recently described frontal components associated with processing within the anterior insular cortex. This work aims to shed light on the effect of task complexity on the insular ERP components associated with perceptual (pN1) and sensory-motor awareness (pP1), as well as with stimulus–response mapping (the pP2). Moreover, this comparison of tasks with different complexity was expected to provide a new point of view on the debate on inhibitory or conflict monitoring role of the N2 component. Thirty-two participants were assigned to two groups: one performed an easy response task (with only a target and a non-target stimulus), the other one performed a complex response task (with two target and two non-target stimuli). The task comparison revealed enhanced pP1 and pP2 components but a reduced N2 component in the complex paradigm. These results suggest that task complexity may entail greater processing strength in the anterior insula functions associated with endogenous perceptual processing. Also, findings on the N2 activity provide evidence against both the inhibitory and conflict interpretation of this component, as the N2 amplitude was reduced in the complex task.