A combined forced-attention dichotic listening - Go/Nogo task to assess response inhibition and interference suppression: An auditory event-related potential investigation

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OBJECTIVE: Interference suppression and response inhibition are distinct effortful inhibitory processes. Yet they rely on partly overlapping neural substrates. Their independence was studied using an auditory paradigm. METHOD: Continuous EEG was recorded in 16 adults and event-related potentials (ERPs) were analyzed in a new dichotic listening - Go/Nogo task. Attention was directed either to the right dominant ear (forced-right blocks [FR]) or to the left ear (forced-left blocks [FL]). The Go/Nogo task required a motor response only to the standard word played to the selected ear; the nonselected ear was simultaneously presented with the same word (Go condition) or with a deviant (Incongruent Go condition). In the Nogo condition, a deviant was presented to the selected ear while the standard was played to the nonselected ear. Effortful interference suppression was expected only in the FL blocks to override the automatic processing of distractors in the dominant ear. RESULTS: When no effortful interference suppression was necessary (FR blocks) in the Nogo condition, the N2 and P3 increase probably reflected two subcomponents of response inhibition (response restraint and response cancellation) and the P2 decrease probably reflected an early inhibitory mechanism (sensory gating). When effortful interference suppression was necessary (FL blocks), there was no Nogo-N2 (i.e., no response restraint). Interference suppression (Incongruent Go condition minus Go condition) also increased the N2 and P3, but did not modulate the P2. CONCLUSIONS: This new paradigm confirms the partial overlap between response inhibition and effortful interference suppression and points out specific features of their subcomponents.