abstract Matthias Wieser

Matthias Wieser (Department of Psychology, Wurzburg University, Germany)

Affective vision - Steady-state visual evoked potential (ssVEPs) studies on preferential processing of social threat cues

In the present talk, I will present several studies which exploited steady-state visual evoked potentials (ssVEPs) to investigate the selection and preferential processing of affective. In addition to conventional ERP research, ssVEPs which are defined by a resonant oscillatory response of visual cortex to repetitive stimulation, offer an avenue to observing electro-cortical facilitation as an index of enhanced attentional engagement. Using frequency tagging (i.e. simultaneously flickering multiple stimuli at different frequencies), it is possible to separate visual cortical activity to spatially overlapping stimuli. Thus, attentional selection and competition can be tested in conditions in which multiple stimuli compete for attention resources. Two experiments are reported where (a) two facial expressions competed for attention resources in spatially separated locations, and (b) a change detection task array was spatially overlaid over a facial expression. Socially anxious participants showed enhanced ssVEP amplitudes to angry faces regardless of a competing face. However, this effect was not observed during the demanding change detection task. It is suggested, that vigilance to threat is sustained in social anxiety but vanishes when attention resources are devoted to non-social stimuli. In further studies, ssVEPs were used to investigate cortical responses to socially conditioned faces. Here, enhanced electrocortical responses were observed for faces previously associated with negative social cues (negative sentences, hand gestures). However, socially anxious participants seem to lack this differentiation between “good” and “bad” guys suggesting a deficit in safety learning. Last, the mutual effects of facial expressions, gaze direction, and affective visual context were explored by assigning two different flicker frequencies to a face and a concurrently presented visual context scene. Cortical processing of fearful faces with averted compared to direct gaze was enhanced only when unpleasant context scenes were presented. Furthermore, fearful faces selectively enhanced the processing of unpleasant background scenes.