Animals in Upright Postures Attract Attention in Humans

Individual predators differ in the level of risk they represent to prey. Because prey incur costs when responding to predators, prey can benefit by adjusting their antipredator behavior based on the level of perceived risk. Prey can potentially assess the level of risk by evaluating the posture of predators as an index of predators' motivational state. Like other prey species, humans might evaluate predator body posture as a prominent cue for assessing danger. We tested whether human participants adjusted their visual attention based on the postures of predators by presenting participants with photographic arrays of predators (lions) that varied in postures while we recorded the participants' gaze behavior. The participants searched for a standing lion (representing a high-risk target) among an array of reclining lions (representing low-risk distractors) or searched for a reclining lion among an array of standing lions. They also searched through similar arrays consisting of non-threatening prey (impalas) standing or reclining, rather than predators. Participants detected standing lions and impala faster than reclining lions and impala. Surprisingly, they detected standing lions at similar latencies as standing impala. They detected the reclining lions and impala more slowly because they spent more time looking at the standing lion and impala distractors and looked at more of those distractors. These results show that upright animals, regardless of whether they are predators or prey, attract attention in humans, and this could allow humans to rapidly evaluate predatory threats or the flight readiness of hunted game.