Venomous snakes elicit stronger fear than nonvenomous ones: Psychophysiological response to snake images

PLoS One. 2020 Aug 19;15(8):e0236999. doi: 10.1371/journal.pone.0236999. eCollection 2020.

Abstract

Snakes have been important ambush predators of both primates and human hunter-gatherers throughout their co-evolutionary history. Viperid snakes in particular are responsible for most fatal venomous snakebites worldwide and thus represent a strong selective pressure. They elicit intense fear in humans and are easily recognizable thanks to their distinctive morphotype. In this study, we measured skin resistance (SR) and heart rate (HR) in human subjects exposed to snake pictures eliciting either high fear (10 venomous viperid species) or disgust (10 nonvenomous fossorial species). Venomous snakes subjectively evaluated as frightening trigger a stronger physiological response (higher SR amplitude) than repulsive non-venomous snakes. However, stimuli presented in a block (more intense stimulation) do not trigger a stronger emotional response compared to sequentially presented stimuli (less intense stimulation). There are significant interindividual differences as subjects with high fear of snakes confronted with images of viperid snakes show stronger, longer-lasting, and more frequent changes in SR and higher HR compared to low-fear subjects. Thus, we show that humans demonstrate a remarkable ability to discriminate between dangerous viperids and harmless fossorial snakes, which is also reflected in distinct autonomous body responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Autonomic Nervous System / physiology
  • Biological Evolution
  • Disgust
  • Fear / physiology*
  • Fear / psychology*
  • Female
  • Galvanic Skin Response / physiology
  • Heart Rate / physiology
  • Humans
  • Male
  • Models, Psychological
  • Photic Stimulation
  • Psychometrics
  • Psychophysiology
  • Snake Bites / psychology*
  • Snake Venoms / poisoning
  • Snakes*
  • Young Adult

Substances

  • Snake Venoms

Grants and funding

This research was funded by GAČR no. 17-15991S (Czech Science Foundation) to EL. Personal costs of all the authors were partly covered by project no. LO1611 under the NPU I program, provided by Ministry of Education, Youth and Sports of the Czech Republic. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. www.gacr.czwww.msmt.cz.