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Landová E, Peléšková Š, Sedláčková K, Janovcová M, Polák J, Rádlová S, Vobrubová B, Frynta D. Venomous snakes elicit stronger fear than nonvenomous ones: Psychophysiological response to snake images. PLoS One 2020; 15:e0236999. [PMID: 32813734 PMCID: PMC7437868 DOI: 10.1371/journal.pone.0236999] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 07/18/2020] [Indexed: 12/22/2022] Open
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.
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Affiliation(s)
- Eva Landová
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Šárka Peléšková
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Kristýna Sedláčková
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Markéta Janovcová
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jakub Polák
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Psychology, Faculty of Arts, Charles University, Prague, Czech Republic
| | - Silvie Rádlová
- National Institute of Mental Health, Klecany, Czech Republic
| | - Barbora Vobrubová
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Daniel Frynta
- National Institute of Mental Health, Klecany, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
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Rádlová S, Polák J, Janovcová M, Sedláčková K, Peléšková Š, Landová E, Frynta D. Emotional Reaction to Fear- and Disgust-Evoking Snakes: Sensitivity and Propensity in Snake-Fearful Respondents. Front Psychol 2020; 11:31. [PMID: 32047463 PMCID: PMC6997343 DOI: 10.3389/fpsyg.2020.00031] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/07/2020] [Indexed: 01/03/2023] Open
Abstract
This paper continues our previous study in which we examined the respondents' reaction to two morphologically different snake stimuli categories - one evoking exclusively fear and another evoking exclusively disgust. Here we acquired Likert-type scale scores of fear and disgust evoked by the same snake stimuli by a total of 330 respondents. Moreover, we collected data about the respondents' age, gender, education, snake fear [Snake Questionnaire (SNAQ)], and disgust propensity [Disgust Scale-Revised (DS-R)], and we analyzed the effect of these variables on the emotional scores (with special focus on snake-fearful respondents). In addition, we collected the SNAQ and DS-R scores from the respondents tested in the previous study using the rank-ordering method to directly compare the results of these two approaches. The results showed that non-fearful respondents give high scores of fear to the fear-eliciting snakes and high scores of disgust to the disgust-eliciting snakes, but they give low scores of the other emotional dimension (disgust/fear) to each. In contrast, snake-fearful respondents not only give higher fear and disgust scores to the respective snake stimuli, but they also give high scores of fear to the disgust-eliciting snakes and high scores of disgust to the fear-eliciting snakes. Both Likert-scale scores and rank-ordering data show that the clear border dividing both snake stimuli categories dissolves when evaluated by the snake-fearful respondents.
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Affiliation(s)
- Silvie Rádlová
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
| | - Jakub Polák
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Psychology, Faculty of Arts, Charles University, Prague, Czechia
| | - Markéta Janovcová
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Kristýna Sedláčková
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Šárka Peléšková
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Eva Landová
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Daniel Frynta
- Applied Neuroscience and Neuroimaging Research Programme, National Institute of Mental Health, Klecany, Czechia
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
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Coelho CM, Suttiwan P, Faiz AM, Ferreira-Santos F, Zsido AN. Are Humans Prepared to Detect, Fear, and Avoid Snakes? The Mismatch Between Laboratory and Ecological Evidence. Front Psychol 2019; 10:2094. [PMID: 31572273 PMCID: PMC6749087 DOI: 10.3389/fpsyg.2019.02094] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 08/28/2019] [Indexed: 12/21/2022] Open
Abstract
Since Seligman (1971) statement that the vast majority of phobias are about objects essential to the survival of a species, a multitude of laboratory studies followed, supporting the finding that humans learn to fear and detect snakes (and other animals) faster than other stimuli. Most of these studies used schematic drawings, images, or pictures of snakes, and only a small amount of fieldwork in naturalistic environments was done. We address fear preparedness theories and automatic fast detection data from mainstream laboratory data and compare it with ethobehavioral information relative to snakes, predator-prey interaction, and snakes' defensive kinematics strikes in order to analyze their potential matching. From this analysis, four main findings arose, namely that (1) snakebites occur when people are very close to the snake and are unaware or unable to escape the bite; (2) human visual detection and escape response is slow compared to the speed of snake strikes; (3) in natural environments, snake experts are often unable to see snakes existing nearby; (4) animate objects in general capture more attention over other stimuli and dangerous, but recent objects in evolutionary terms are also able to be detected fast. The issues mentioned above pose several challenges to evolutionary psychology-based theories expecting to find special-purpose neural modules. The older selective habituation hypothesis (Schleidt, 1961) that prey animals start with a rather general predator image from which specific harmless cues are removed by habituation might deserve reconsideration.
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Affiliation(s)
- Carlos M. Coelho
- Department of Psychology, Faculty of Psychology, Chulalongkorn University, Bangkok, Thailand
| | - Panrapee Suttiwan
- Department of Psychology, Faculty of Psychology, Chulalongkorn University, Bangkok, Thailand
| | - Abul M. Faiz
- Department of Psychology, Dev Care Foundation, Dhaka, Bangladesh
| | - Fernando Ferreira-Santos
- Department of Psychology, Laboratory of Neuropsychophysiology, Faculty of Psychology and Education Sciences, University of Porto, Porto, Portugal
| | - Andras N. Zsido
- Department of General and Evolutionary Psychology, Institute of Psychology, University of Pécs, Pécs, Hungary
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