Stimuli

We examined a list of extant snake species inhabiting Europe, the Mediterranean and Caspian area (Uetz et al., 2015). For this study, we selected 36 species covering the main morphological diversity and all major phylogenetic lineages. The included species belong to 6 families and 29 genera (Pyron et al., 2013; Uetz et al., 2015; for more information about the tested snakes, see Supplementary Table 1). To test perceived fear and beauty, we developed a standardized set of 36 photographs depicting these species, each representing a typical adult individual in a resting position. In addition, we included a control photograph of the Egyptian cobra (Naja haje) in a striking posture for a comparison with the resting position picture. The photos were adapted from books and internet sources (for sources and other information, see Supplementary Table 4). We digitally set the pictures of snake bodies on a white background, resized them to a comparable size (regardless of their real size) using GIMP2.8.16 (GNU Image Manipulation Program. Spencer Kimball, Peter Mattis et al., 1995 – 2015), and printed them in a 10 × 15 cm format. It has been previously demonstrated that photos may reliably substitute live snakes (Landová et al., 2012).