Effect of spatial frequency on threat-related perceptual decision making of facial emotion

Abstract

Research on perceptual prioritization of threat-related stimuli has focused on the classical lowroad hypothesis, which stressed the automaticity of threat detection driven by the evolutionary saliency of the stimuli. Such automaticity is postulated to arise from a fast, subcortical neural pathway running from the magnocellular neurons to the amygdala, and it has been shown that these magnocellular neurons are particularly sensitive to low- (LSF) but not high- spatial frequency (HSF) visual information. Despite a considerable amount of neural evidence supporting the “low-road” pathway under bottom-up attention, there is a paucity of research that systematically examined the functional role of the “low-road” pathway behaviorally on threat-related perceptual decision making under top-down and bottom-up attention. Using a novel perceptual decision-making paradigm, we found that when the endogenous attention was directed toward the emotional information of the face, LSF images of fearful face yielded poorer performance (i.e., lower accuracy, poorer perceptual sensitivity, and more conservative response bias) compared with HSF images of fearful face. In contrast, when the emotional information of the face is task-irrelevant, differences in the performance between HSF and LSF images were no longer observed. These findings suggest that threat-related perceptual decision making of facial emotion under top-down attention does not rely on the “low-road” pathway. This thesis offers behavioral evidence to propose that the putative functional role of the “lowroad” pathway in threat-related perceptual decision making of facial emotion depends on the demand of the task which alters the focus of endogenous attention on different aspects of the face.