Abstrakt
Snakes are ancestrally prioritized stimuli that preferentially attract human attention and evoke fear due to the past risks they pose to us. Some snakes also elicit not only fear, but also disgust.
We tested the subjectively perceived level of fear and disgust elicited by 80 pictures of snake species and tested the associations with scores on self-report questionnaires measuring snake fear (SNAQ) or disgust propensity (DS-R). For some snakes, we measured physiological fear and disgust correlates as triggered by pictures presented to respondents individually or in a block design.
Results from cluster analysis demonstrate that people perceive fear- and disgust-evoking snakes as two distinct stimulus groups. Analysis of morphological traits of snakes revealed that fear is mostly triggered by viper and rattlesnake body form, while disgust is mainly associated with subterranean snakes with a worm-like body shape.
The physiological parameters (changes in skin conductance) in a reaction to fear-evoking snakes are repeatable despite the different style of stimuli presentation (individually vs. block), but reaction to disgusting snakes is not. Subjective evaluations according to the given emotion are positively correlated with scores on the SNAQ and less on the DS-R.
People are subjectively aware of the two emotions, although only the physiological reaction to fearful snakes was repeatable. This is in accordance with the hypothesis of snakes as prototypical stimuli for activation of fear module.
Only certain morphotypes of snakes serve as a specific prototypical stimulus though, which raise further reflections on the co-evolution of some snake taxa and mankind.