Emotional arousal elicited by irrelevant stimuli affects event-related potentials (ERPs) during response inhibition

Previous event-related potential (ERP) studies using the Go/Nogo task have indicated that response inhibition is influenced by the arousal elicited by emotional stimuli, when those stimuli are relevant to response selection of Go and Nogo trials. Due to stimulus and task design issues, however, it is uncertain whether response inhibition is affected by emotional valence or arousal, when emotional stimuli are irrelevant to response selection. Therefore, the present study aimed to re-investigate this issue by circumventing limitations of previous research. To address this issue, thirty-one young adults (16 females and 15 males) were required to make motor responses to frequently-presented faces of one sex (Go trials) and to inhibit responses to less-frequently presented faces of the opposite sex (Nogo trials). Crucially, the faces were superimposed onto positive, negative and neutral pictures. The pictures were presented in a randomized order. The arousal values between positive and negative pictures were highly matched. Results showed that Nogo faces elicited smaller N2 but larger P3a amplitudes, when the faces were associated with positive and negative pictures as compared to neutral pictures. These findings suggest that response inhibition is influenced by emotional arousal, when emotional stimuli are irrelevant to response selection. Additionally, for Go faces, results showed smaller N2 but larger P3a amplitudes within negative pictures as compared to neutral and positive pictures, suggesting a role of emotional valence elicited by irrelevant stimuli on response execution.