Humans detect snakes more accurately and quickly than other animals under natural visual scenes: a flicker paradigm study

Threat detection is crucial to survival. Studies using unnatural visual scene settings (i.e. visual search tasks) have shown that humans and primates are able to identify snakes more quickly than they are able to identify other animals. The present study employed a flicker paradigm task to assess whether humans detect snakes more accurately and rapidly than they do other reptiles in natural scene settings. Participants watched a long series of images, consisting of pairs of complex natural scenes. A blank interval was inserted between the two versions of the scene, showing only the scene and the scene plus an added animal (snake or lizard). Participants detected scene changes featuring the snake targets more accurately and rapidly than those with lizard targets. This finding supports the view that there were evolutionary pressures for a visual system which prioritised human detection of snakes.