Rapid withdrawal from threatening animals is movement-specific and mediated by reflex-like neural processing

Abstract

Responses to potentially dangerous stimuli are among the most basic animal behaviors. While research has shown that threats automatically capture the attention of human participants, research has failed to demonstrate automatic behavioral responses to threats in humans. Using a naturalistic paradigm, we show that two species of animals humans often report fearing trigger rapid withdrawal responses: participants withdrew their arm from photos of snakes and spiders faster, and with higher acceleration when compared to bird and butterfly stimuli. The behavioral was specific to withdrawal as approach movements, or button-press/release tasks failed to detect a similar difference. Using electroencephalography (EEG), we show that the fast withdrawal was mediated by two attentional processes. First, fast withdrawal responses correlated with early amplification of sensory signals (P1, 70-110 ms after stimulus). Second, a later correlate of feature-based attention (early posterior negativity, EPN, 200-240 ms after stimulus) revealed the opposite pattern: Stronger EPN was associated with slower behavioral responses, suggesting that the deployment of attention towards threatening stimulus features was detrimental for withdrawal speed. Altogether, the results suggest that rapid behavioral withdrawal from threatening animals in humans is mediated by reflex-like attentional processing.