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Štolhoferová I, Frynta D, Janovcová M, Rudolfová V, Elmi HSA, Rexová K, Berti DA, Král D, Sommer D, Landová E, Frýdlová P. The bigger the threat, the longer the gaze? A cross-cultural study of Somalis and Czechs. Front Psychol 2023; 14:1234593. [PMID: 37829068 PMCID: PMC10565226 DOI: 10.3389/fpsyg.2023.1234593] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 09/13/2023] [Indexed: 10/14/2023] Open
Abstract
High fear reaction, preferential attention, or fast detection are only a few of the specific responses which snakes evoke in humans. Previous research has shown that these responses are shared amongst several distinct cultures suggesting the evolutionary origin of the response. However, populations from sub-Saharan Africa have been largely missing in experimental research focused on this issue. In this paper, we focus on the effect of snake threat display on human spontaneous attention. We performed an eye-tracking experiment with participants from Somaliland and the Czechia and investigated whether human attention is swayed towards snakes in a threatening posture. Seventy-one Somalis and 71 Czechs were tested; the samples were matched for gender and comparable in age structure and education level. We also investigated the effect of snake morphotype as snakes differ in their threat display. We found that snakes in a threatening posture were indeed gazed upon more than snakes in a relaxed (non-threatening) posture. Further, we found a large effect of snake morphotype as this was especially prominent in cobras, less in vipers, and mostly non-significant in other morphotypes. Finally, despite highly different cultural and environmental backgrounds, the overall pattern of reaction towards snakes was similar in Somalis and Czechs supporting the evolutionary origin of the phenomenon. We concluded that human attention is preferentially directed towards snakes, especially cobras and vipers, in threatening postures.
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Affiliation(s)
- Iveta Štolhoferová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Markéta Janovcová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Veronika Rudolfová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Hassan Sh Abdirahman Elmi
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
- Department of Biology, Faculty of Education, Amoud University, Borama, Somalia
| | - Kateřina Rexová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Daniel Alex Berti
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - David Král
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - David Sommer
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
| | - Petra Frýdlová
- Department of Zoology, Faculty of Science, Charles University, Prague, Czechia
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Rudolfová V, Štolhoferová I, Elmi HSA, Rádlová S, Rexová K, Berti DA, Král D, Sommer D, Landová E, Frýdlová P, Frynta D. Do Spiders Ride on the Fear of Scorpions? A Cross-Cultural Eye Tracking Study. Animals (Basel) 2022; 12:ani12243466. [PMID: 36552386 PMCID: PMC9774548 DOI: 10.3390/ani12243466] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022] Open
Abstract
Deep fear of spiders is common in many countries, yet its origin remains unexplained. In this study, we tested a hypothesis based on recent studies suggesting that fear of spiders might stem from a generalized fear of chelicerates or fear of scorpions. To this end, we conducted an eye tracking experiment using a spontaneous gaze preference paradigm, with spiders and scorpions (previously neglected but crucial stimuli) as threatening stimuli and grasshoppers as control stimuli. In total, 67 participants from Somaliland and 67 participants from the Czech Republic were recruited and presented with a sequence of paired images. Both Somali and Czech people looked longer (total duration of the gaze) and more often (number of fixations) on the threatening stimuli (spiders and scorpions) when presented with a control (grasshopper). When both threatening stimuli were presented together, Somali participants focused significantly more on the scorpion, whereas in Czech participants, the effect was less pronounced, and in Czech women it was not significant. This supports the hypothesis that fear of spiders originated as a generalized fear of scorpions. Moreover, the importance of spiders as fear-eliciting stimuli may be enhanced in the absence of scorpions in the environment.
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Affiliation(s)
- Veronika Rudolfová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Iveta Štolhoferová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Hassan S. A. Elmi
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
- Department of Biology, Faculty of Education, Amoud University, Borama, Somaliland
| | - Silvie Rádlová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Kateřina Rexová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Daniel A. Berti
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - David Král
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - David Sommer
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
| | - Petra Frýdlová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
- Correspondence:
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43 Prague, Czech Republic
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Coss RG, Charles EP. The Saliency of Snake Scales and Leopard Rosettes to Infants: Its Relevance to Graphical Patterns Portrayed in Prehistoric Art. Front Psychol 2021; 12:763436. [PMID: 34880813 PMCID: PMC8645795 DOI: 10.3389/fpsyg.2021.763436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/27/2021] [Indexed: 12/17/2022] Open
Abstract
Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistoric cave and mobiliary art. Two experiments examined the saliency of snake scales and leopard rosettes to infants that are perceptually analogous to these patterns. Experiment 1 examined the investigative behavior of 23 infants at three daycare facilities. Four plastic jars (15×14.5cm) with snake scales, leopard rosettes, geometric plaid, and plain patterns printed on yellowish-orange paper inside were placed individually on the floor on separate days during playtime. Fourteen 7–15-month-old infants approached each jar hesitantly and poked it before handling it for five times, the criterion selected for statistical analyses of poking frequency. The jars with snake scales and leopard rosettes yielded reliably higher poking frequencies than the geometric plaid and plain jars. The second experiment examined the gaze and grasping behavior of 15 infants (spanning 5months of age) seated on the laps of their mothers in front of a table. For paired comparisons, the experimenter pushed two of four upright plastic cylinders (13.5×5.5cm) with virtually the same colored patterns simultaneously toward each infant for 6s. Video recordings indicated that infants gazed significantly longer at the cylinders with snake scales and leopard rosettes than the geometric plaid and plain cylinders prior to grasping them. Logistic regression of gaze duration predicting cylinder choice for grasping indicated that seven of 24 paired comparisons were not significant, all of which involved choices of cylinders with snake scales and leopard rosettes that diverted attention before reaching. Evidence that these biological patterns are salient to infants during an early period of brain development might characterize the integration of subcortical and neocortical visual processes known to be involved in snake recognition. In older individuals, memorable encounters with snakes and leopards coupled with the saliency of snake scales and leopard rosettes possibly biased artistic renditions of similar patterns during prehistoric times.
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Affiliation(s)
- Richard G Coss
- Psychology Department, University of California, Davis, Davis, CA, United States
| | - Eric P Charles
- Psychology Department, University of California, Davis, Davis, CA, United States
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Lau AR, Grote MN, Dufek ME, Franzetti TJ, Bales KL, Isbell LA. Titi monkey neophobia and visual abilities allow for fast responses to novel stimuli. Sci Rep 2021; 11:2578. [PMID: 33510399 PMCID: PMC7844259 DOI: 10.1038/s41598-021-82116-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 01/15/2021] [Indexed: 01/30/2023] Open
Abstract
The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems. Although many studies using different methods have found very rapid snake detection in catarrhines, including humans, to date no studies have examined how quickly platyrrhine primates can detect snakes. We therefore tested in captive coppery titi monkeys (Plecturocebus cupreus) the latency to detect a small portion of visible snake skin. Because titi monkeys are neophobic, we designed a crossover experiment to compare their latency to look and their duration of looking at a snake skin and synthetic feather of two lengths (2.5 cm and uncovered). To test our predictions that the latency to look would be shorter and the duration of looking would be longer for the snake skin, we used survival/event time models for latency to look and negative binomial mixed models for duration of looking. While titi monkeys looked more quickly and for longer at both the snake skin and feather compared to a control, they also looked more quickly and for longer at larger compared to smaller stimuli. This suggests titi monkeys' neophobia may augment their visual abilities to help them avoid dangerous stimuli.
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Affiliation(s)
- Allison R Lau
- Animal Behavior Graduate Group, University of California, Davis, Davis, CA, 95616, USA.
- California National Primate Research Center, University of California, Davis, Davis, CA, 95616, USA.
- Department of Psychology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA.
| | - Mark N Grote
- Department of Anthropology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Madison E Dufek
- California National Primate Research Center, University of California, Davis, Davis, CA, 95616, USA
| | - Tristan J Franzetti
- California National Primate Research Center, University of California, Davis, Davis, CA, 95616, USA
- Department of Biology, Duke University, Durham, NC, 27708, USA
| | - Karen L Bales
- Animal Behavior Graduate Group, University of California, Davis, Davis, CA, 95616, USA
- California National Primate Research Center, University of California, Davis, Davis, CA, 95616, USA
- Department of Psychology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Lynne A Isbell
- Animal Behavior Graduate Group, University of California, Davis, Davis, CA, 95616, USA
- Department of Anthropology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
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Jensen CH, Caine NG. Preferential snake detection in a simulated ecological experiment. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021; 175:895-904. [PMID: 33417722 DOI: 10.1002/ajpa.24224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 12/17/2020] [Accepted: 12/20/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVES According to Isbell's snake detection theory (SDT), the need to rapidly detect and thus avoid snakes had a major impact on the evolution of the primate visual system, and thus the origin and evolution of the primate lineage, as expansion of the visual sense is a key characteristic of primates. The SDT rests on the assumption that there are both cortical (conscious) and subcortical (unconscious) brain structures and pathways that are responsible for rapid visual detection of and quick avoidance reactions to snakes. Behavioral evidence for the SDT primarily comes from visual search tasks and presentations of images on a computer screen; our aim was to evaluate the SDT under more ecologically valid circumstances. MATERIALS AND METHODS We asked participants to take a virtual hike in which a realistic model of a snake, rabbit, or bottle had been placed on the trail. Subjects were instructed simply to imagine themselves as the hiker while watching the video. We measured heart rate and skin conductance reactions while the participants viewed the video. After the video, the participants were shown pictures of the three stimuli and asked if they had seen any of them. RESULTS We found that snakes were detected more often than rabbits or bottles, and that participants showed greater changes in heart rate and greater skin conductance responses in the snake condition than in the other two conditions, even when the participant did not report having seen the snake. DISCUSSION A critical component of the SDT is that primates must be able to quickly detect snakes even when their attention is directed elsewhere. Using a novel experimental context-a simulated hike-we assessed arousal and detection without directing participants to attend to any particular stimulus or event. Our data support the SDT by providing evidence of enhanced detection and autonomic arousal even in the absence of detection. Replication of these results using additional controls and experimental contexts will help refine our understanding of snake avoidance by primates.
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Affiliation(s)
- Cody H Jensen
- Department of Psychology, California State University San Marcos, San Marcos, California, USA
| | - Nancy G Caine
- Department of Psychology, California State University San Marcos, San Marcos, California, USA
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Coss RG, Cavanaugh C, Brennan W. Development of snake-directed antipredator behavior by wild white-faced capuchin monkeys: III. the signaling properties of alarm-call tonality. Am J Primatol 2019; 81:e22950. [PMID: 30664280 DOI: 10.1002/ajp.22950] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/14/2018] [Accepted: 11/30/2018] [Indexed: 12/17/2022]
Abstract
In many primates, the acoustic properties of alarm calls can provide information on the level of perceived predatory threat as well as influence the antipredator behavior of nearby conspecifics. The present study examined the harmonics-to-noise ratio (tonality of spectral structure) of alarm calls emitted by white-faced capuchin monkeys (Cebus capucinus) in trees directed at photographic models of a boa constrictor, neotropical rattlesnake, scorpion eater snake, and white snake-shaped control presented on the ground. The average and peak harmonics-to-noise ratios of initial alarm calls by infants, juveniles, and adults and those of nearby second callers were analyzed using PRAAT software. Averaged for age class, the peak harmonics-to-noise ratio of alarm calls directed at the boa constrictor model, characterizing a primary capuchin predator, was reliably higher than the peak harmonics-to-noise ratio of alarm calls directed at the harmless scorpion eater model. This effect was influenced by the higher harmonics-to-noise ratio of infant alarm calls and it disconfirmed our prediction, based on primate vocalization research, that snake perception would increase arousal and alarm-call noisiness. Levels of call tonality did not distinguish the boa and rattlesnake or rattlesnake and scorpion eater models for any age class. Higher alarm-call tonality appeared contagious to nearby perceivers, with focal alarm calling influencing the level of tonality of the first calls of second callers. Together, these findings suggest that the higher peak harmonics-to-noise ratio of capuchin alarm calling directed at snakes is contagious and possibly conveys information about the level of perceived predatory threat.
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Affiliation(s)
- Richard G Coss
- Department of Psychology, University of California, Davis, California.,Graduate Group in Animal Behavior, University of California, Davis, California
| | - Cailey Cavanaugh
- Department of Psychology, University of California, Davis, California
| | - Whitney Brennan
- Graduate Group in Animal Behavior, University of California, Davis, California
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Isbell LA, Etting SF. Scales drive detection, attention, and memory of snakes in wild vervet monkeys (Chlorocebus pygerythrus). Primates 2016; 58:121-129. [DOI: 10.1007/s10329-016-0562-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 08/07/2016] [Indexed: 12/17/2022]
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