Vigilance: A novel conditioned fear response that resists extinction.

Attentional bias for threat is an adaptive feature of human psychology, but may become maladaptive in anxiety-related disorders, causing distress, distraction, and distorted perception of danger. Reaction time measures have revealed automatic, covert attention biases to threat, whereas eye tracking has revealed voluntary biases over a larger timescale, with monitoring or avoidance depending on context. Recently, attentional bias for threat has been studied as a conditioned fear response, providing new insight into how attentional biases are acquired and inhibited through learning experiences. However, very few studies have examined voluntary gaze biases during fear learning. In a novel eye tracking paradigm (N = 78), we examine the overt components of attentional bias to threat and safety cues. We found that threat cues, but not safety cues, elicited an initial orienting bias, as well as sustained monitoring bias across 10-second trials. This collective "vigilance" response to threat cues was insensitive to extinction, whereas condition fear responding revealed by pupil size and self-report ratings showed marked extinction. Vigilance may be less prone to extinction, compared to autonomic arousal, because eye movements require less energy than preparing the body for defensive behavior. Implications for understanding vigilance in PTSD are considered.