Snakes are stimuli inducing an ancestral fear response in humans and other primates. Certain snakes evoke more subjective fear than others. True vipers are high-fear-eliciting snakes for both African and European respondents. This can be explained by the evolutionary experience of human ancestors in Africa. The question arises as to how snakes living in the Americas and Australia, with which humans have no evolutionary experience, will be evaluated. While these snakes belong to broader taxonomic groups that have distant relatives in the Old World, they have evolved independently for tens of millions of years. We prepared a set of 32 pictures depicting eight American pit vipers, eight Australian elapids, eight constrictors, and eight colubrids and asked the respondents to rank these stimuli according to the fear these snakes evoke. Here, we show a high cross-cultural agreement between evaluations by African and European respondents. Snakes characterized by a robust body shape, such as American pit vipers, Australian death adders, pythons, and boas, were the most fear-evoking. The body width was the strongest predictor of evoked fear. The contribution of coloration and pattern of the stimulus to the fear response was not proved. This supports the view that the patterns of fear are not dependent on direct experience, but its underlying mechanisms are shared cross-culturally.

• Keywords
• Boidae, Elapidae, Viperidae, cross-cultural comparison, evolutionary psychology, fear, ophidiophobia,
• Publication type
• Journal Article MeSH

Fear of snakes is common not only in humans but also in other primates. Consequently, snakes are salient stimuli associated with prioritized attention, early detection and emotional significance. This has been interpreted as an adaptive evolutionary response of the primate brain to a risk of envenoming by a hidden snake. However, the struggle between mammals and snakes is not one-sided. Humans and carnivores regularly kill snakes, and thus snakes develop deterring defensive behaviour that may directly evoke enhanced fear. Here, we show that snakes depicted in threatening posture evoked on average more fear than those in resting posture. Significantly, African (Somali) and European (Czech) respondents considerably agreed on the relative fear elicited by various snakes. Nonetheless, not all defensive postures are equally efficient. Threatening cobras were perceived as top fear-evoking stimuli, even though most of them are not considered very frightening in resting posture. This effect can be attributed to their conspicuous hooding posture which evolved into an efficient warning signal for mammalian predators. Our result demonstrates that cobras are more effective than other snakes in the ability to evoke human fear by a simple behavioural display-hooding. This can be primarily explained by the behavioural evolution of cobras which successfully exploited pre-existing cognitive mechanisms of mammals. Whether human ancestors cohabiting with deadly venomous cobras further improved their fear response to hooding is uncertain, but likely.

• Keywords
• Cross-cultural comparison, Evolutionary psychology, Fear, Hooding, Ophidiophobia, Specific phobias,
• MeSH
• Elapidae physiology   MeSH
• Snakes * physiology   MeSH
• Humans MeSH
• Fear * physiology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Snakes are known as highly fear-evoking animals, eliciting preferential attention and fast detection in humans. We examined the human fear response to snakes in the context of both current and evolutionary experiences, conducting our research in the cradle of humankind, the Horn of Africa. This region is characterized by the frequent occurrence of various snake species, including deadly venomous viperids (adders) and elapids (cobras and mambas). We conducted experiments in Somaliland and compared the results with data from Czech respondents to address the still unresolved questions: To which extent is human fear of snakes affected by evolutionary or current experience and local culture? Can people of both nationalities recognize venomous snakes as a category, or are they only afraid of certain species that are most dangerous in a given area? Are respondents of both nationalities equally afraid of deadly snakes from both families (Viperidae, Elapidae)? We employed a well-established picture-sorting approach, consisting of 48 snake species belonging to four distinct groups. Our results revealed significant agreement among Somali as well as Czech respondents. We found a highly significant effect of the stimulus on perceived fear in both populations. Vipers appeared to be the most salient stimuli in both populations, as they occupied the highest positions according to the reported level of subjectively perceived fear. The position of vipers strongly contrasts with the fear ranking of deadly venomous elapids, which were in lower positions. Fear scores of vipers were significantly higher in both populations, and their best predictor was the body width of the snake. The evolutionary, cultural, and cognitive aspects of this phenomenon are discussed.

• Keywords
• cross-cultural comparison, evolutionary psychology, fear, ophidiophobia, specific phobias,
• Publication type
• Journal Article MeSH

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.

• Keywords
• Africa, Snake detection theory, eye-tracking, snake, spontaneous attention,
• Publication type
• Journal Article MeSH

Theories explain the presence of fears and specific phobias elicited by animals in contemporary WEIRD (Western, educated, industrialized, rich, and democratic) populations by their evolutionary past in Africa. Nevertheless, empirical data about fears of animals in the Cradle of Humankind are still fragmentary. To fill this gap, we examined which local animals are perceived as the most frightening by Somali people, who inhabit a markedly similar environment and the region where humans have evolved. We asked 236 raters to rank 42 stimuli according to their elicited fear. The stimuli were standardized pictures of species representing the local fauna. The results showed that the most frightening animals were snakes, scorpions, the centipede, and large carnivores (cheetahs and hyenas). These were followed up by lizards and spiders. Unlike in Europe, spiders represent less salient stimuli than scorpions for Somali respondents in this study. This conforms to the hypothesis suggesting that fear of spiders was extended or redirected from other chelicerates.

• Keywords
• African savanna, Arachnophobia, Evolutionary psychology, Fear, Non-WEIRD, Ophidiophobia,
• MeSH
• Phobic Disorders * MeSH
• Snakes MeSH
• Humans MeSH
• Spiders * MeSH
• Scorpions MeSH
• Fear MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Spiders are mostly harmless, yet they often trigger high levels of both fear and disgust, and arachnophobia (the phobia of spiders) ranks among the most common specific animal phobias. To investigate this apparent paradox, we turned to the only close relatives of spiders that pose a real danger to humans: scorpions. We adopted a unique methodology in order to assess authentic emotions elicited by arthropods. Over 300 respondents were asked to rate live specimens of 62 arthropod species (including spiders, scorpions, cockroaches, and other insects) based on perceived fear, disgust, and beauty. We found that species' scores on all three scales depended on the higher taxon as well as on body size. Spiders, scorpions, and other arachnids scored the highest in fear and disgust, while beetles and crabs scored the highest in beauty. Moreover, all chelicerates were perceived as one cohesive group, distinct from other arthropods, such as insects or crabs. Based on these results, we hypothesize that the fear of spiders might be triggered by a generalized fear of chelicerates, with scorpions being the original stimulus that signals danger.

• MeSH
• Arthropods * MeSH
• Adult MeSH
• Emotions * MeSH
• Phobic Disorders etiology   psychology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Spiders * MeSH
• Surveys and Questionnaires MeSH
• Aged MeSH
• Cluster Analysis MeSH
• Fear psychology   MeSH
• Animals MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

To investigate a specificity of spiders as a prototypical fear- and disgust-eliciting stimuli, we conducted an online experiment. The respondents rated images of 25 spiders, 12 non-spider chelicerates, and 10 other arthropods on a fear and disgust 7-point scale. The evaluation of 968 Central European respondents confirmed the specificity of spiders among fear- and disgust-eliciting arthropods and supported the notion of spiders as a cognitive category. We delineated this category as covering extant spider species as well as some other chelicerates bearing a physical resemblance to spiders, mainly whip spiders and camel spiders. We suggested calling this category the spider-like cognitive category. We discussed evolutionary roots of the spider-like category and concluded that its roots should be sought in fear, with disgust being secondary of the two emotions. We suggested other chelicerates, e.g., scorpions, might have been important in formation and fixation of the spider-like category. Further, we investigated an effect of respondent's sensitivity to a specific fear of spiders on evaluation of the stimuli. We found that suspected phobic respondents were in their rating nearly identical to those with only high fear of spiders and similar to those with only moderate fear of spiders. We concluded that results based on healthy respondents with elevated fear should also be considered relevant for arachnophobia research.

• MeSH
• Arthropods MeSH
• Adult MeSH
• Emotions MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Disgust * MeSH
• Spiders * MeSH
• Aged MeSH
• Fear psychology   MeSH
• Personality Assessment MeSH
• Animals MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Animals have always played an important role in our everyday life. They are given more attention than inanimate objects, which have been adaptive during the evolution of mankind, with some animal species still presenting a real threat to us. In this study, we focused on the species usually evaluated as the scariest and most disgusting in the animal kingdom. We analyzed which characteristics (e.g., weight, potential threat for humans) influence their evaluation in a nonclinical Central European WEIRD population (Western, educated, industrialized, rich, and democratic). The tested animals were divided into two separated sets containing 34 standardized photos evoking predominantly one negative emotion, fear or disgust. The pictures were ranked according to their emotional intensity by 160 adult respondents with high inter-rater agreement. The most fear-eliciting species are mostly large vertebrates (e.g., carnivorans, ungulates, sharks, crocodiles), whereas smaller fear-evoking vertebrates are represented by snakes and invertebrates are represented by arachnids. The most disgust-evoking animals are human endo- and ectoparasites or animals visually resembling them. Humans emotionally react to fear-evoking animals that represent a real threat; however, identifying truly dangerous disgust-evoking animals might be harder. The results also support a somewhat special position of snakes and spiders.

• Keywords
• animals, disgust, fear, human–animal relationship, negative emotions,
• Publication type
• Journal Article MeSH

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.

• MeSH
• Autonomic Nervous System physiology   MeSH
• Biological Evolution MeSH
• Adult MeSH
• Galvanic Skin Response physiology   MeSH
• Snake Venoms poisoning   MeSH
• Snakes * MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Disgust MeSH
• Psychophysiology MeSH
• Models, Psychological MeSH
• Psychometrics MeSH
• Heart Rate physiology   MeSH
• Fear physiology   psychology   MeSH
• Photic Stimulation MeSH
• Snake Bites psychology   MeSH
• Animals MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Snake Venoms MeSH

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.

• Keywords
• DS-R, SNAQ, disgust, emotional response, fear, image rating, self-reported emotion, snake phobia,
• Publication type
• Journal Article MeSH