Are Humans Prepared to Detect, Fear, and Avoid Snakes? The Mismatch Between Laboratory and Ecological Evidence

Abstract

Since Seligman (1971) statement that the vast majority of phobias are about objects essential to the survival of a species, a multitude of laboratory studies followed, supporting the finding that humans learn to fear and detect snakes (and other animals) faster than other stimuli. Most of these studies used schematic drawings, images, or pictures of snakes, and only a small amount of fieldwork in naturalistic environments was done. We address fear preparedness theories and automatic fast detection data from mainstream laboratory data and compare it with ethobehavioral information relative to snakes, predator-prey interaction, and snakes’ defensive kinematics strikes in order to analyze their potential matching. From this analysis, four main findings arose, namely that (1) snakebites occur when people are very close to the snake and are unaware or unable to escape the bite; (2) human visual detection and escape response is slow compared to the speed of snake strikes; (3) in natural environments, snake experts are often unable to see snakes existing nearby; (4) animate objects in general capture more attention over other stimuli and dangerous, but recent objects in evolutionary terms are also able to be detected fast. The issues mentioned above pose several challenges to evolutionary psychology-based theories expecting to find special-purpose neural modules. The older selective habituation hypothesis (Schleidt, 1961) that prey animals start with a rather general predator image from which specific harmless cues are removed by habituation might deserve reconsideration.

Emotional Reaction to Fear- and Disgust-Evoking Snakes: Sensitivity and Propensity in Snake-Fearful Respondents

“…Even though the mortality rates attributed to serpents in the prehistoric times cannot be reliably quantified due to the snake highly efficient metabolism leaving no fossil records of their prey (Greene, 1983;Hsiang et al, 2015), some circumstantial evidence suggests that the emergence of snakes must have become a strong selection pressure in the mammalian evolution (Öhman and Mineka, 2003). As a consequence of the risk presented by snakes, human ancestors have developed a complex adaptive system of interconnected fear responses manifested on the psychological, behavioral, physiological, and neural level, which, according to some authors, has been embodied in a specific brain area, the so-called module of fear (Öhman and Mineka, 2001) localized in the amygdala (Öhman, 2005; Öhman et al, 2007; for a recent critical review of the modular theory, see Coelho et al, 2019). In fact, the modular theory has drawn upon the much earlier Seligman's (1971) concept of biological preparedness claiming that most of the clinical fears are triggered by stimuli threatening our survival in the evolutionary past.…”

Venomous snakes elicit stronger fear than nonvenomous ones: Psychophysiological response to snake images

“…Alternatively, the stronger physiological response to venomous snakes found in our study might as well be explained by the need of activating energetic resources in dangerous situations, which is necessary for a fast and effective defense (fight-or-flight) response before a snakebite can be delivered, i.e., eliminate the source of threat or rather withdraw oneself from the snake's presence. However, in their latest review on presumed preparedness of fear of snakes, Coelho et al [51] argue, that most snakebites happen at very close vicinity and are extremely fast, so the victim usually has no chance to effectively respond.…”

Circles Are Detected Faster Than Downward-Pointing Triangles in a Speeded Response Task

“…They suggested a relevancebased explanation rather than an evolutionary-based explanation of threat detection. Interestingly, Coelho et al (2019) reported several challenges to evolutionary-based explanations of the snake detection theory and highlighted that the low-level features of the visual stimulus could have affected previous findings. Wolfe (2018) also suggested threat perception as a probable nonguiding attribute in visual search when the other basic features are controlled for.…”