Primates may have neurons specialized to detect snakes.
In macaque monkeys:
But, there is always a caution:
In macaque monkeys:
They found that images of snakes had a particularly strong and fast-acting effect on pulvinar neurons: Of the 91 neurons that became active at some point in the experiment, 40% were “snake-best,” meaning they were more active during snake photos than other images. These neurons also fired more frequently than the ones responding to faces, hands, or shapes. (Neurons responding to angry faces, an important social threat for the highly social macaques, came in second.) Finally, snake-responsive neurons sprang into action more quickly, activating about 15 milliseconds faster than those that responded to angry faces and about 25 milliseconds ahead of the neutral shape-detecting neurons.
But, there is always a caution:
The results support the idea that primates have built-in mechanisms for recognizing a very specific threat based on its shape, says Isabelle Blanchette, a cognitive psychologist at the University of Quebec, Trois-Rivières, in Canada who studies the role of emotion in how we process information. But she warns that we should resist the urge to extrapolate to humans. Even if we carry these “leftovers from evolution” in the form of snake-sensitive neurons deep in our visual system, higher brain processes, such as learning and memory, may influence our behavior just as much as this deep and instinctive snake sense. “It’s a very important part of the picture, but it is only a part,” she says. Her research has shown that humans aren’t always faster at detecting snakes than other threats, including guns and cars, which we haven’t evolved to fear innately.
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macgupta 81p · 595 weeks ago
Isabelle Blanchette
Snakes, spiders, guns, and syringes: How specific are evolutionary constraints on the detection of threatening stimuli?
The Quarterly Journal of Experimental Psychology
Volume 59, Issue 8, 2006
Abstract
In three experiments, the efficiency in detecting fear-relevant and fear-irrelevant visual stimuli are compared. A visual search paradigm is used where participants are presented with matrices of different sizes (4 objects/9 objects) and must determine whether all objects are taken from the same category or whether there is a discrepant one. Results from all experiments were consistent with the threat-superiority effect. Participants were quicker when the target was threatening than when it was not. Other indicators confirmed that the detection of threatening targets involves more efficient processes (reduced slopes, absence of position effects). A crucial aspect of these experiments was the comparison of evolutionary-relevant (snakes, spiders, etc.) and modern (guns, syringes, etc.) threats. The threat-superiority effect was repeatedly found for both types of target. Stronger effects were sometimes observed for modern than for evolutionary-relevant threats. The implications for evolutionary explanations of the effect of fear on visual attention are discussed.
macgupta 81p · 595 weeks ago
The detection of fear-relevant stimuli: Are guns noticed as quickly as snakes?
Fox, Elaine; Griggs, Laura; Mouchlianitis, Elias
Emotion, Vol 7(4), Nov 2007, 691-696. doi: 10.1037/1528-3542.7.4.691
Abstract
Potentially dangerous stimuli are important contenders for the capture of visual-spatial attention, and it has been suggested that an evolved fear module is preferentially activated by stimuli that are fear relevant in a phylogenetic sense (e.g., snakes, spiders, angry faces). In this study, a visual search task was used to test this hypothesis by directly contrasting phylogenetically (snakes) and ontogenetically (guns) fear-relevant stimuli. Results showed that the modern threat was detected as efficiently as the more ancient threat. Thus, both guns and snakes attracted attention more effectively than neutral stimuli (flowers, mushrooms, and toasters). These results support a threat superiority effect but not one that is preferentially accessed by threat-related stimuli of phylogenetic origin. The results are consistent with the view that faster detection of threat in visual search tasks may be more accurately characterized as relevance superiority effects rather than as threat superiority effects. (PsycINFO Database Record (c) 2012 APA, all rights reserved)