Snakes that look alike draw similar fear and disgust in a 377-person photo study

Sorting the ratings first and explaining them afterwards keeps the experimenters' own guesses about which snakes look dangerous out of the groups ^[6]. Each image was rated on six scales: fear, disgust, beauty, emotional valence, arousal and perceived size ^[5]. Those ratings were reduced to three profiles ^[1]. The team then examined "whether these different profiles were associated with the animals' visual and morphological characteristics, as well as with participants' individual experience and attitudes," Soares said ^[16].

The photo set had a neat control built into it. "We also included a small number of elongated, limbless reptiles that look remarkably snake-like but are not actually snakes, which helped us explore whether people were responding to the animal's biological identity or to its visual characteristics," said Luiz Biondi, the paper's first author ^[4][14].

Soares's lab came to this question from work on how quickly primates detect snakes ^[9]. Earlier studies suggest that humans, as well as monkeys and apes, tend to notice snakes in their surroundings fast ^[9]. "Fast visual detection of something as a snake is not necessarily the same as being afraid of it," Soares told Phys.org ^[8]. The next question, she said, was "what makes some snakes appear more threatening than others once we actually look at them?" ^[15] A 2025 review by her group examined evidence that different visual features of snakes can become important at different stages of perception ^[13].

Her reasoning starts from ecology. In her words, "a slender colubrid, a broad-headed viper and a large constrictor may all be snakes, but they provide very different visual information" ^[10]. Participants also reported their general fear of snakes, previous encounters with them and exposure to natural environments ^[5]. That let the study ask how responses "interact with individual experience and ecological or cultural context" ^[11]. Phys.org's account does not list the traits behind each profile, or say where the non-snakes landed.

With participants from only Brazil and Portugal ^[2], the cultural comparison has two points. The study extends work by Daniel Frynta and colleagues suggesting that people respond differently to different snake species ^[12].