The evil eye effect: vertical pupils are perceived as more threatening

Area of Science:

• Evolutionary psychology
• Visual perception
• Human-animal interactions

Background:

• Humans possess an evolutionary history of rivalry with snakes.
• Vertical pupils are a characteristic of ambush predators, including certain snakes.
• Popular culture often associates vertical pupils with evil characters.

Purpose of the Study:

• To investigate whether humans perceive vertical pupils as threatening.
• To explore the evolutionary basis of this perception, particularly its link to snake detection.
• To determine if the perceived threat is physical or social.

Main Methods:

• Seven studies were conducted with a total of 1458 participants from American and Turkish samples.
• Perception of threat associated with vertical pupils was assessed using explicit and implicit measures.
• The relationship between snake phobia and the perception of vertical pupils as threatening was examined.

Main Results:

• Vertical pupils were consistently perceived as more threatening on both explicit and implicit levels.
• The perceived threat was primarily associated with physical danger, not social threat.
• Snake phobia, but not spider phobia, correlated with perceiving vertical pupils as threatening.

Conclusions:

• Vertical pupils evoke a threatening perception in humans, potentially rooted in evolutionary predispositions.
• Findings offer partial support for the role of snake detection mechanisms in this response.
• The study highlights the complex interplay between evolutionary history, visual cues, and threat perception.