Toward a reliable detection of arachnophobia: subjective, behavioral, and neurophysiological measures of fear response

IntroductionThe administration of questionnaires presents an easy way of obtaining important knowledge about phobic patients. However, it is not well known how these subjective measurements correspond to the patient’s objective condition. Our study aimed to compare scores on questionnaires and image evaluation to the objective measurements of the behavioral approach test (BAT) and the neurophysiological effect of spiders extracted from fMRI measurements. The objective was to explore how reliably subjective statements about spiders and physiological and behavioral parameters discriminate between phobics and non-phobics, and what are the best predictors of overall brain activation.MethodsBased on a clinical interview, 165 subjects were assigned to either a “phobic” or low-fear “control” group. Finally, 30 arachnophobic and 32 healthy control subjects (with low fear of spiders) participated in this study. They completed several questionnaires (SPQ, SNAQ, DS-R) and underwent a behavioral approach test (BAT) with a live tarantula. Then, they were measured in fMRI while watching blocks of pictures including spiders and snakes. Finally, the respondents rated all the visual stimuli according to perceived fear. We proposed the Spider Fear Index (SFI) as a value characterizing the level of spider fear, computed based on the fMRI measurements. We then treated this variable as the “neurophysiological effect of spiders” and examined its contribution to the respondents’ fear ratings of the stimuli seen during the fMRI using the redundancy analysis (RDA).ResultsThe results for fear ranks revealed that the SFI, SNAQ, DS-R, and SPQ scores had a significant effect, while BAT and SPQ scores loaded in the same direction of the first multivariate axis. The SFI was strongly correlated with both SPQ and BAT scores in the pooled sample of arachnophobic and healthy control subjects.DiscussionBoth SPQ and BAT scores have a high informative value about the subject’s fear of spiders and together with subjective emotional evaluation of picture stimuli can be reliable predictors of spider phobia. These parameters provide easy and non-expensive but reliable measurement wherever more expensive devices such as magnetic resonance are not available. However, SFI still reflects individual variability within the phobic group, identifying individuals with higher brain activation, which may relate to more severe phobic reactions or other sources of fMRI signal variability

Evolutionary consequences of species specific learning strategies:importance of processes resulting in food aversion and special case of social transmission.

This PhD. thesis contributes to the investigation of aposematism - the phenomenon explaining the occurrence of warning colouration in nature. Aposematism is an antipredatory strategy usually based on predator learning to avoid a noxious prey with a conspicuous signal. However, not only particular aspects of aposematic prey signalling (warning colour pattern, conspicuousness, unpalatability), but also predator's psychology leading to avoidance behaviour is an important factor for explaining the evolution of aposematism. The differential species-specific response of our common passerine birds to living aposematic prey (the firebug) and corresponding underlying variation in predator's ecology requirements has been the starting point of this PhD. thesis. The next parts of the present thesis have been focused mainly on the species responding positively (innate biases, learning, memory etc.) to the warning signal of aposematic prey. We investigate the diversity of psychological processes leading to avoidance behaviour in these species. Firstly, we investigate if the avoidance behaviour is acquired by learning or if the prey is avoided on the basis of innate biases in several species of the family Paridae. We focused on the mode of avoidance learning and the durability of the acquired behaviour in the..

Evolutionary consequences of species specific learning strategies: importance of processes resulting in food aversion and special case of social transmission

t t Summary This PhD. thesis contributesto the investigationof aposematism- the phenomenonexplaining occuÍTenceof warning coloration in nature. Aposematismis anantipredatorystrategyousuallybasedonpredatorlearning to avoid a noxious prey with a conspicuoussignal. However, not only particularaspectsof aposematicprey signalling (waming colour pattern, conspicuousness,unpalatability),but also predator'spsychologyleadingto avoidancebehaviouris animportantfactorin theevolutionof aposematism. The differentialspecies-specificresponseof nine speciesof our conrmon passerine birds to living aposematicprey (the ťrebug) and correspondingunderlyingvariationin predator'secolory requirements has beenstartingpointof thisPhD.thesis. The next partsof the presentthesishavebeenfocusedmainly on determinationof thesespeciesthat respondspositively (throughoutinnate biases,betterlearningor memoryetc.)to the warningsignalof aposematic prey. The diversity of psychological processes leading to avoidance behaviourin thesespecieshas beenassessed.Firstly, we investigateif the avoidancebehaviouris acquiredby learningor ifthe preyis avoidedon the basisof innatebiasesin severalspeciesof family Paridae. Thenwe focused onmodeof avoidanceleaminganddurabilityof acquiredbehaviourin model species(greattits).The changesin memoryfor..

Human Preferences for Colorful Birds: Vivid Colors or Pattern?

In a previous study, we found that the shape of a bird, rather than its color, plays a major role in the determination of human preferences. Thus, in the present study, we asked whether the preferences of human respondents towards uniformly shaped, colorful birds are determined by pattern rather than color. The experimental stimuli were pictures of small passerine birds of the family Pittidae possessing uniform shape but vivid coloration. We asked 200 participants to rank 43 colored and 43 identical, but grayscaled, pictures of birds. To find the traits determining human preferences, we performed GLM analysis in which we tried to explain the mean preference ranks and PC axes by the following explanatory variables: the overall lightness and saturation, edges (pattern), and the portion of each of the basic color hues. The results showed that the mean preference ranks of the grayscale set is explained mostly by the birds' pattern, whereas the colored set ranking is mostly determined by the overall lightness. The effect of colors was weaker, but still significant, and revealed that people liked blue and green birds. We found no significant role of the color red, the perception of which was acquired relatively recently in evolution

Experimental Crossing of Two Distinct Species of Leopard Geckos, Eublepharis angramainyu and E. macularius: Viability, Fertility and Phenotypic Variation of the Hybrids.

Hybridization between distinct species of animals and subsequent genetic introgression plays a considerable role in the speciation process and the emergence of adaptive characters. Fitness of between-species hybrids usually sharply decreases with the divergence time of the concerned species and the divergence depth, which still allows for a successful crossing differs among principal clades of vertebrates. Recently, a review of hybridization events among distinct lizard species revealed that lizards belong to vertebrates with a highly developed ability to hybridize. In spite of this, reliable reports of experimental hybridizations between genetically fairly divergent species are only exceptional. Here, we show the results of the crossing of two distinct allopatric species of eyelid geckos possessing temperature sex determination and lacking sex chromosomes: Eublepharis macularius distributed in Pakistan/Afghanistan area and E. angramainyu, which inhabits Mesopotamia and adjacent areas. We demonstrated that F1 hybrids were viable and fertile, and the introgression of E. angramainyu genes into the E. macularius genome can be enabled via a backcrossing. The examined hybrids (except those of the F2 generation) displayed neither malformations nor a reduced survival. Analyses of morphometric and coloration traits confirmed phenotypic distinctness of both parental species and their F1 hybrids. These findings contrast with long-term geographic and an evolutionary separation of the studied species. Thus, the occurrence of fertile hybrids of comparably divergent species, such as E. angramainyu and E. macularius, may also be expected in other taxa of squamates. This would violate the current estimates of species diversity in lizards

Association Between Fear and Beauty Evaluation of Snakes: Cross-Cultural Findings

According to the fear module theory, humans are evolutionarily predisposed to perceive snakes as prioritized stimuli and exhibit a fast emotional and behavioral response toward them. In Europe, highly dangerous snake species are distributed almost exclusively in the Mediterranean and Caspian areas. While the risk of a snakebite is relatively low in Central Europe, Azerbaijan, on the other hand, has a high occurrence of the deadly venomous Levant viper (Macrovipera lebetina). We hypothesize that co-habitation with this dangerous snake has shaped the way in which humans evaluate snake species resembling it. For that purpose, we asked respondents from the Czech Republic and Azerbaijan to rank photographs depicting 36 snake species according to perceived fear and beauty. The results revealed a high cross-cultural agreement in both evaluations (fear r2 = 0.683, p < 0.0001; beauty: r2 = 0.816, p < 0.0001). Snakes species eliciting higher fear tend to be also perceived as more beautiful, yet people are able to clearly distinguish between these two dimensions. Deadly venomous snakes representing a serious risk are perceived as highly fearful. This is especially true for the vipers and allies (pit vipers) possessing a characteristic body shape with a distinct triangular head and thick body, which was found as the most fear evoking by respondents from both countries. Although the attitude toward snakes is more negative among the respondents from Azerbaijan, their fear evaluation is similar to the Czechs. For instance, despite co-habitation with the Levant viper, it was not rated by the Azerbaijanis as more fearful than other dangerous snakes. In conclusion, agreement in the evaluation of snake fear and beauty is cross-culturally high and relative fear attributed to selected snake species is not directly explainable by the current environmental and cultural differences. This may provide some support for the evolutionary hypothesis of preparedness to fear snakes

Box plots of hatchling snout-vent lengths.

<p><i>E</i>. <i>macularius</i> (n = 32), <i>E</i>. <i>angramainyu</i> (n = 4), their hybrids of the first (F₁; n = 25) and second (F₂; n = 3) filial generations and the reciprocal backcrosses of F₁ males or females to the <i>E</i>. <i>macularius</i> (B_1M; the individuals with father F₁ hybrid are denoted as MxMA, while those with the mother F₁ hybrid as MAxM; n = 11 and 16, respectively). Median, quartiles and ranges are provided.</p

Box plots of adult snout-vent lengths.

<p><i>E</i>. <i>macularius</i> (n = 68), <i>E</i>. <i>angramainyu</i> (n = 15), their hybrids of the first filial generation (F₁; n = 27), and its reciprocal backcrosses of F₁ males or females to the <i>E</i>.<i>macularius</i> (B_1M; the individuals with the father F₁ hybrid are denoted as MxMA, while those with the mother F₁ hybrid as MAxM; n = 10 and 17, respectively). Median, quartiles and ranges are provided.</p