Changes in neural processing and evaluation of negative facial expressions after administration of an open-label placebo

A recent event-related potential (ERP) study found that an open-label placebo (OLP) reduced emotional distress during the viewing of unpleasant scenes and the amplitude of the late positive potential (LPP). The present ERP experiment aimed at a conceptual replication of this finding and investigated OLP effects during affective face processing. The participants (109 females) were presented with images depicting angry and neutral facial expressions after the administration of a saline nasal spray. The spray was either introduced as a placebo that could help reduce the emotional reactions to viewing angry faces (OLP group) or to improve the electrophysiological recordings (Control group). The OLP was associated with reduced LPP amplitudes (1000–6000 ms) to anger expressions across a frontal cluster. Additionally, the OLP reduced LPP amplitudes (400–1000 ms) to both anger and neutral faces across a centroparietal cluster. Compared to the Control group, the OLP group reported less arousal when confronted with angry faces, and rated the anger expressions as less intense. This study demonstrates that an OLP can alter both subjective and neural responses to anger cues. Future research should directly compare OLP treatment with other strategies for emotion regulation (e.g., cognitive reappraisal) to demonstrate the specificity of this approach.