Do Snakes Draw Attention More Strongly than Spiders or Other Animals?

Abstract

Adults detect pictures of snakes and spiders more quickly than pictures of mushrooms or flowers. The same holds true for pictures of fear-irrelevant animals which are detected more quickly than pictures of non-animal objects, however pictures of fear-relevant animals (i.e., snakes and spiders) are detected more quickly than are pictures of fear-irrelevant animals (such as birds and fish). In addition, fear-relevant animals (i.e., snakes and spiders) draw attention more strongly than do fear-irrelevant but repulsive animals (such as lizards and cockroaches). These results substantiate the fear module theory (Ohman and Mineka, Psychol Rev 108:483-522, 2001). However, recent studies have shown that spiders do not draw attention as strongly as do snakes. We conducted visual search tasks in which fear-relevant (snakes or spiders) and fear-irrelevant stimuli (Experiment 1, flowers or mushrooms; Experiment 2, koalas or birds) were presented as both target stimuli and distractors (Shibasaki and Kawai 2011). Snakes captured attention more than spiders did when snakes were target stimuli, while snakes held attention more strongly than spiders did when snakes were distractors. A series of studies investigating the attention-drawing power of snakes and spiders under conditions of greater perceptual load indicated that while snakes automatically drew attention even under high perceptual load, the same was not true for spiders. In a visual search study we conducted using monkeys, we found that while snakes were detected among fear-irrelevant animals (koalas) more quickly than vice versa, the time required to detect spiders among koalas was about the same (i.e., was not faster) than the time required for the reverse. These results deviate from the original fear module theory and instead are consistent with the snake detection theory (SDT), which holds that snakes are the only animals that have always been feared by humans and primates.