Explicit Semantic Stimulus Categorization Interferes With Implicit Emotion Processing Abbreviated title: Interference with Emotion Processing

2 Previous fMRI-and ERP-studies revealed that performing a cognitive task may suppress the preferential processing of emotional stimuli. However, these studies utilized simple and artificial tasks (i.e., letter, shape, or orientation discrimination tasks), unfamiliar to the participants. The present event-related potential study examined the emotion-attention interaction in the context of a comparably more natural scene categorization task. Deciding whether a natural scene contains an animal or not is a familiar and meaningful task to the participants and presumed to require little attentional resources. The task images were presented centrally and were overlaid upon emotional or neutral background pictures. Thus, implicit emotion and explicit semantic categorization may compete for processing resources in neural regions implicated in object recognition. Additionally, participants passively viewed the same stimulus materials without the demand to categorize task images. Significant interactions between task condition and emotional picture valence were observed for the occipital negativity and late positive potential. In the passive viewing condition, emotional background images elicited an increased occipital negativity followed by an increased late positive potential. In contrast, during the animal-/non-animal-categorization task, emotional modulation effects were replaced by strong target categorization effects. These results suggest that explicit semantic categorization interferes with implicit emotion processing when both processes compete for shared resources. 3 The preferential processing of high-priority stimuli in the environment is an essential function of selective attention. Emotional stimuli may command attentional resources and priority processing due to their intrinsic stimulus significance (Lang et al., 1997, Schupp et al., 2006). Research utilizing event-related brain potentials (ERPs) determined that the processing of high-arousing pleasant and unpleasant compared to low-arousing control images is associated with a negative-going potential over temporo-occipital sensor regions around 150-300 ms poststimulus. This occipital negativity effect may reflect a transitory processing period within which emotional stimuli are selected for elaborate processing compared to neutral and non-arousing stimulus processing is associated with an enlarged late positive potential between 300-700 ms poststimulus. The LPP is considered as a measure of the allocation of processing resources in a capacity-limited processing stage associated with timing reveal various effects of selective attention brought out by emotionally salient stimuli. A number of studies have explored emotional stimulus processing while participants concurrently performed a primary cognitive task. fMRI-and ERP studies demonstrated that focusing visual attention on stimuli relevant to the current task goals interfered with the preferential processing of emotionally relevant stimuli, which were unrelated to the primary task …