13 December 2013

Afraid of Snakes?

Welcome back. If you’re old enough to be a member of AARP, you might have seen the pronouncement in the Oct/Nov 2013 issue of their magazine that people over 50 are more afraid of snakes than they are of running out of money.
Visitor (probably a black rat snake),
about 4 feet long, that welcomed Rachel
home one day. (It’s not a great photo--
Rachel was leaving too fast.)
(www.rachelphilipson.com)

I’m not sure about the source of the survey statistics. The AARP item, Upfront, mentioned a study from the University of Texas at Austin, though I don’t think that was the source and couldn’t confirm any link from the cited author’s publications.

I considered querying the editor but decided that was unnecessary. I’m sure you’ll agree that, whether or not they’re Number 1, snakes are way up there on the phobia list. (For general reference, ophidiophobia is fear of snakes; herpetophobia is the more general fear of reptiles or amphibians, or both.)

Here’s the thing. I would have ignored the AARP note if I hadn’t just seen two studies--one recent, one older--that suggest our brains have been wired to detect snakes.

Older Study

A 2008 study from the University of Virginia provided evidence that our ability to detect snakes and other “fear-relevant stimuli” (e.g., spiders) was enhanced through evolution.

In a series of experiments, adults and preschool children were shown single-target pictures among arrays of eight distractors. The adults and even the children spotted snakes quicker than they spotted three types of nonthreatening stimuli (flowers, frogs and caterpillars).

Although young children may not fear snakes, they’re especially adept at detecting them and are predisposed to learn to fear snakes.

Recent Study

A recently published study, this one by collaborators from Japan’s University of Toyama, the University of California, Davis, and Brazil’s University of Brasilia, provides neuroscientific evidence to support the idea that the threat of snakes strongly influenced the evolution of the primate brain. (Primates include apes, monkeys and us.)

The researchers tested two macaque monkeys that were born on a national monkey farm in Japan and had probably never seen snakes. To measure the activity of individual brain cells, they implanted microelectrodes in a part of the monkeys’ brain’s visual system that’s unique to primates.

When the monkeys were shown images of snakes and three other stimulus categories--threatening monkey faces, monkey hands and geometric shapes--the Images of the snakes elicited the strongest, fastest responses (and the responses were not reduced by low spatial filtering of the images).

Wrap Up

Although my review of research was far from comprehensive and although further research is needed, particularly with primates that have never been exposed to real or imaged snakes or stories thereof, it seems that we’re primed to fear snakes. Whether it began with a bite or an apple, that fear has apparently grown over the millennia; at least that’s what surveys such as that reported by AARP suggest. Thanks for stopping by.

P.S.

- Older (2008) study in Psychological Science Journal:
pss.sagepub.com/content/19/3/284.abstract
- Article on older study on Live Science:
www.livescience.com/2348-fear-snakes.html
- Recent study in Proceedings of the National Academy of Sciences:
www.pnas.org/content/early/2013/10/23/1312648110
- Articles on recent study from National Public Radio and the Times of India:
www.npr.org/blogs/health/2013/10/29/241370496/eeek-snake-your-brain-has-a-special-corner-just-for-them
articles.timesofindia.indiatimes.com/2013-10-29/science/43494975_1_snakes-primates-monkeys


P.P.S.

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