Fearful faces straight ahead or in the periphery: Early neuronal responses independently of trait anxiety.

Abstract

For humans, it is vitally important to rapidly detect potentially threatening stimuli such as fearful faces in the periphery. Trait anxiety has been related to biased responses to threatening faces, which might be more pronounced for peripheral stimuli. We examined the impact of spatial location and trait anxiety on event-related potentials to fearful faces (ERPs) in a large sample (N = 80). Using a face-unrelated oddball detection task and online eye-tracking, we ensured central fixation but sustained attention to the location of fearful and neutral faces at central or peripheral locations (12° left or right). Manipulation checks showed high task performance and successful shifts of visuospatial attention indexed by prestimulus alpha lateralization of the EEG spectra. Concerning ERPs, we observed increased P1 amplitudes for fearful compared to neutral faces, independent of the spatial location. In contrast, the N170 to fearful faces was only potentiated for centrally presented faces. Finally, fearful and neutral faces did not differ during the EPN window at any spatial location. Trait anxiety was unrelated to fearful-neutral ERP differences for each examined location. Our findings show that differential P1 responses are less constrained by the stimulus location, possibly due to coarse low-level stimulus information processing. However, the relative N170 increase for fearful faces depends on the central stimulus location. Furthermore, findings support the view that differential processing at the stage of the EPN depends on attentional conditions. Finally, our results question the hypothesis that trait anxiety differences correlate with mandatorily altered processing of threatening stimuli.