Why are so many people arachnophobes (have an extreme fear of spiders)?

  • $\begingroup$ Related: cogsci.stackexchange.com/questions/9200/… $\endgroup$ – Arnon Weinberg Mar 4 '16 at 23:24
  • $\begingroup$ Somewhat related read here and here. Those studies found that among other sub-types of specific phobia, animals types are one of the most common. And the focus of fear of this type is "disgust" or "revulsion". $\endgroup$ – Nono Mar 5 '16 at 6:33
  • $\begingroup$ And another study here found that even among other disgusting animal (cockroaches), children and adults detected spiders more rapidly. Perhaps because spiders are not just disgusting, but also dangerous (venomous), but I have yet to find research claiming this. $\endgroup$ – Nono Mar 5 '16 at 6:36

The answer can be found from evolutionary psychology. We are wired to feel fear when we encounter stimulus that look like spiders and snakes.

Evolutionary psychologists argue that much of human behavior is the
output of psychological adaptations that evolved to solve recurrent
problems in human ancestral environments

Spiders and snakes were major threads in the early years of the evolutionary history of humans. Human ancestors that were more afraid of spiders/snakes had an evolutionary advantage over those who did not, because they were more cautious and survived more years.

people nonetheless learn to fear spiders and snakes about as easily as they do a pointed gun, and more easily than an unpointed gun, rabbits or flowers. A potential explanation is that spiders and snakes were a threat to human ancestors throughout the Pleistocene, whereas guns (and rabbits and flowers) were not. There is thus a mismatch between humans' evolved fear-learning psychology and the modern environment.


Humans are most comfortable with those things that resemble themselves, both in terms of physical features and mentality. A dog, for example, may have an extra set of legs and a tail, but does not differ all that significantly from humans or other mammals—we can similarly see ourselves in the behavior and apparent emotions they exhibit.

Arachnids, on the other hand, are several orders of magnitude more alien. Beyond the gross physical dissimilarities, it is impossible to attribute anything resembling human emotion or motivation to them. Add to that their penchant for appearing unexpected in dark places and their inherently predatory nature, the very idea of spiders triggers in many people a primordial dread.

  • 3
    $\begingroup$ This argument is not very specific. It would equally apply to many animals that people are not afraid of or just find disgusting. For instance, woodlice are physiologically very different and are found in dark place, but are not commonly associated with phobias. $\endgroup$ – Joe Bathelt Mar 6 '16 at 9:53

A quick lit scan suggests evolutionary advantage to being afraid of spiders and snakes. Unclear what causes this mechanism: http://news.nationalgeographic.com/news/2001/10/1004_snakefears.html

Social conditioning also likely plays a huge role here. Spiders in our society are seen as evil / scary (via Halloween, movies, etc.). This unconscious bias makes people naturally afraid of bugs and spiders through social conditioning and social physics.


According to the American Psychiatric Association, phobias affect more than one in ten people in the US, and of those individuals, up to 40% of phobias are related to bugs (including spiders), mice, snake and bats.

There are clearly a lot of arachnophobes. But do they know why they fear spiders? Can they do something to control those fears?

Once bitten twice shy?

Psychologists believe that one reason why people fear spiders is because of some direct experience with the arachnids instilled that fear in them. This is known as the “conditioning” view of arachnophobia.

There was also an effect from family. Those people fearful of spiders reported having a family member with similar fears, but the study was unable to separate genetic factors from environmental ones.

Not surprisingly, if you give kids a list of things that might be scary for them, the vast majority check off things like not breathing, getting hit by a car, bombs, fire or burglars as quite important. Interestingly, if you give them a free option to tell researchers what sorts of things they fear the most, both boys and girls report “spiders” as their top fear (the second fear is being kidnapped, third is predators and fourth is the dark).

This is surprising. Of all the things kids might report, they list spiders as the number one fear. So in contrast to Davey’s work, Muris finds that the kids that were most fearful of spiders could relate that fear to specific events. Perhaps conditioning is the pathway to arachnophobia.


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