Are blood-injection-injury stimuli different from other negative categories? An ERP study.

Brain electrical potentials are valid indicators of motivated attention in affective picture processing but differential processing of stimulus categories with specific motivational relevance has hardly been addressed in the past. In this study we aimed to investigate whether specific stimulus related processes can be determined as assessed by ERP components, independently of valence and arousal. Forty participants viewed pictures of categories Disgust, blood-injection-injury (BII), Fear, and Neutral during EEG recording. Amplitudes of event-related potentials of P200, P300 and late positive potential (LPP) were assessed. Viewing visual stimuli of affectively relevant categories elicited typical ERPs with increased amplitudes in P300 and LPP time windows at parietal sites compared to neutral stimuli. In addition P200 amplitude was the largest for BII compared to all other categories. P300 amplitude was the largest for BII stimuli and was comparable to fear after controlling for P200 amplitude. Our data suggest that a distinction of stimulus categories by motivational relevance is important in addition to the dimensional categorization by means of valence and arousal and that motivated attention alone is not sufficient for the interpretation of our data. Moreover, our data indicate that processing of distinct stimulus categories, in particular that of BII stimuli, evolves differentially in time. Altogether, ERPs rather reflect the motivational relevance of stimuli and not simple arousal.