Stimulus preceding negativity represents arousal induced by affective picture

In this study, we investigated the effect of affective valence on the stimulus-preceding negativity (SPN) using the international affective picture system (IAPS). We adopted a S1-S2 paradigm, in which the subject could know the content of the forthcoming affective-slide (positive, negative or neutral picture) by the S1 cue (three types of gray-and-white striped squares). Our procedure differentiated these affective valences which were assessed by questionnaires. The self-assessment mannequin (SAM) data showed that the emotional score (pleasantness) significantly increased in the order of negative, neutral, and positive picture. The arousal scores of the SAM and the multiple mood scale (MMS) for negative picture were higher than for the other pictures. The SPN over the frontal regions significantly increased preceding the negative pictures, but not preceding the neutral and positive pictures. Our results suggest that the SPN might represent arousal induced by emotion-inducing pictures.