Red Diffuse Light Suppresses the Accelerated Perception of Fear

Prioritization of affective events may occur via two parallel pathways originating from the retina—a parvocellular (P) pathway projecting to ventral-stream structures responsible for object recognition or a faster and phylogenetically older magnocellular (M) pathway projecting to dorsal-stream structures responsible for localization and action. It has previously been demonstrated that retinal exposure to red diffuse light suppresses M-cell neural activity. We tested whether the fast propagation along the dorsal-action pathway drives an accelerated conduction of fear-based content. Using a visual prior-entry procedure, we assessed accelerated stimulus perception while either suppressing the M pathway with red diffuse light or leaving it unaffected with green diffuse light. We show that the encoding of fearful faces is accelerated, but not when M-channel activity is suppressed, revealing a dissociation that implicates a privileged neural link between emotion and action that begins at the retina.