The role of awareness and specific phobias in visual perception and autonomic responses to threatening animals

Numerous studies have investigated the unconscious processing of evolutionary threatening animals. Researchers have discovered an advantage in the unconscious processing of snake and spider images, as evidenced by higher detection abilities and stronger electrodermal activity. Moreover, individuals with specific phobias tend to exhibit enhanced behavioral and autonomic responses toward their feared animal. However, this advantage in the unconscious processing of evolutionary threatening animals has not been consistently supported. The present study aimed to comprehensively investigate the mechanisms underlying the unconscious perception of threatening animals, in both healthy and phobic participants. We used the “breaking Continuous Flash Suppression” technique to subliminally present spider and snake images for a prolonged period of time. We recorded the time needed for the stimuli to break through suppression as well as different physiological indices, including electrodermal activity (EDA), facial electromyography (EMG), and pupil dilation. We also administered three questionnaires measuring the levels of arachnophobia (SPQ-12), ophidiophobia (SNAQ-12), and negative emotions (DASS-21). We found faster breakthrough times for snakes compared to spiders, with quicker responses for intact images than for their scrambled versions. Snakes and spiders were associated with higher electrodermal responses and greater pupil dilation compared to their scrambled counterparts, even before the stimuli reached visual awareness. Arachnophobe participants showed greater EDA when presented with spiders compared to scrambled images, but only when consciously perceived. Overall, our results support the existence of a subcortical pathway that facilitates a preattentive processing of threatening stimuli.