Inside the human revulsion (disgust) reflex
Human Behavioral observations by Don Burleson
What is the nature of revulsion and disgust? What is it about
a festering corpse that invokes the gag reflex? Why is it
funny when your boss farts loudly in a crowded elevator? If
you can stomach it, see my blog for
Personally, some of my grossest experience are related to working with
occasionally develop "projectile diarrhea" and they can shoot a stream
of liquid poo up to 12 feet behind them.
I also recall a
situation where I was riding a horse with sinus congestion (a horses
nasal cavity can be a foot long) and imagine my revulsion when the horse
reared-back his head and tossed a softball-sized wad of gooey phlegm
into my face.
Dead Rat found in pickle
I studied psychology in college (BA, 1979), and I've always been fascinated
with the nature of global human behaviors. Behaviors that are uniform
across the world can be teased-out to reveal the truly universal human
behaviors, manifestations of our basest raw instinct, instinctive reactions
without any cultural or social bias. One such universal behavior is
revulsion, the natural squeamish behavior that once served to protect our bodies
from carrion and now has become a major entertainment phenomenon.
Television revels in the revolting reflex (Fear Factor, The Surgery Channel,
&c) and movies such as Apocalypto and "300" where we witness numerous beheadings
and organs ripped from live bodies. This revulsion reaction has many
- Revolting - (revulsion)
- Gross - (gross-out, grossed-out)"
- Disgusting - (with disgust)
Lets face it. people love to become disgusted,
and there are even kids books like "Gross
Universe" dedicated to gross things for kids. Professor Paul
Rozin (known widely as "Dr. Disgust"), has
this paper where he examines the nature
of revulsion. and he shares these observations on the "disgust" response,
suggesting that it's both instinct and culture:
"Disgust evolves culturally," explains Rozin, "and develops from a system
to protect the body from harm to a system to protect the soul from harm."
At its root, disgust is a revulsion response -- "a basic biological
motivational system" -- that Darwin associated with the sense of taste.
Its function is to reject or discharge offensive-tasting food from the
mouth (and/or the stomach), and its fundamental indicator, the "gape" or
tongue extension, has been observed in a number of animals, including birds
Psychology Today article notes that
Darwin also researched this fascinating topic:
"Charles Darwin, in his classic book The Expression of Emotions in Man
and Animals, took perhaps the earliest scientific look at disgust. . . .By
putting his finger on the meat, the Indian helped Darwin put his finger on
three key aspects of disgust: first, that it can be elicited by quite
different things--in this case, food and people; second, it is an emotion
shared by radically diverse cultures; and third, what different cultures
consider gross can vary tremendously.
Darwin then inventoried the physiological reactions to disgusting things.
At one end of the scale is a frown, often accompanied by hand gestures or
body language aimed at pushing away or shielding against the repulsive
This article titled "Total
recoil" notes: "Chances are, there's a special something that's
guaranteed to turn your stomach. Perhaps it's the sight and smell of a
decomposing pigeon at the side of the pavement, maggots wriggling from its
vacant eye sockets. Or perhaps you squirm whenever you think of your
grandma's mucky dentures by her bedside."
Why do we like being revolted? What's the exact nature of gross-out
humor? Well, I think that I've got it figured out. Let's take a
It's revolting - the universal human reflex
The revulsion reflex refers to something so gross, so revolting, that it
invokes your gag reflex. This includes festering and putrid meat, feces,
and images of mutilation (such as televised live surgeries). The
first question is whether we can identify any world-wide discernable differences
by a major demographic such as "age" or "gender".
- Inappropriate sex acts (bestiality, necrophilia)
- Putrid, decaying foods, carrion
- Gore (Not the guy who invented the Internet)
- Physical deformities (warts, gaping wounds)
- Cigarette smokers (mostly in California)
This article titled "Total
recoil" notes their list of universal items of revulsion:
- Bodily secretions - feces (poo), vomit, sweat, spit, blood,
pus, sexual fluids
- Body parts - wounds, corpses, toenail clippings
- Decaying food - especially rotting meat and fish, rubbish
- Certain living creatures - flies, maggots, lice, worms, rats,
dogs and cats
- People who are ill, contaminated"
Psychology Today article notes that the
core response of disgust is both instinctual and learned: "We are
socialized by our disgust and, in turn, use it to socialize others; what better
way is there to stop people from doing something socially undesirable than to
"make" that something--whether eating rancid meat or, in India, defying the
We can easily judge peoples reactions to revolting stimuli, but how can we
infer differences? Let's start with the age factor:
Sigmund Freud observed that revulsion toward feces is a learned behavior, no
surprise to any parent. Babies and toddlers appear in have no
sophisticated gag reflex (although they will readily refuse spoiled food).
Having raised a few kids, I'm confident that toddlers don't have the same
standards of revulsion as adults. They seem to find poo fascinating, and
they have no qualms cleaning-out the cat's litter box by-hand. I've
seen kids who will eat whatever unfortunate insects who happen by, and I've seen
more than one toddler who will reach into the back of their diaper and show you
As kids enter the prepubescent stage of development (ages 4 to 9), they
generally develop a revulsion behavior toward feces, and yet there are wide
differences with respect to reacting with revulsion to multination behavior.
Some children are extremely squeamish (the kid who faints when getting a
vaccination), yet we also see kids who
Are the gender differences in revulsion behavior?
I do not believe that there is a gender influence in revulsion, but we
certainly see a gross-out gender bias it in the media. I once witnessed a
teenage girl go into convulsive revulsion, all because she picked-out a terrier
and he pee'ed all over her hands, and yet I've seen macho men with such a low
revulsion reflex that they would gag while changing a dirty diaper, while I've
witnessed women who were impervious to revulsion.
My son once found a dead chicken in an old barn when he lifted an over-turned
bucket. (Evidently, the chicken knocked the bucket down from a high wall and it
happened to land right on her, where she died from thirst.) She had been
dead awhile and was very putrid, with dripping gelatinous goo replacing the
torso. There are very few people who can clean-up something like that
without experiencing revulsion.
The movie industry is making zillions of dollars, delivering gross-out
masterpieces such as "Apocalypto", "300", and "The Passion", movies with the
sole intent to invoke the human revulsion behavior. On TV, we see shows
like "South Park" that relish in the realm of the revolting, where almost every
episode features revolting images. In one episode, squeamish viewers were
treated to a medical film documenting the "cutting" during a male-female sex
change surgery (According to comedian Tim Allen, the medical term for this
member removal procedure is "Lop-it-off-o-me").
Once such universal reflex is "revulsion", a modern manifestation of the gag
reflex that kept our caveman ancestors from eating rabbit that had been dead too
long. Today the revulsion instinct is memorialized in popular TV shows
like "Fear Factor" where we can watch
Measuring the revulsion response
This person has an interesting "disgust
Circle T (true) or F (false):
T F 1. It bothers me to see someone in a restaurant eating messy food with
T F 2. It would not upset me at all to watch a person with a glass eye take
the eye out of the socket.
T F 3. I never let any part of my body touch the toilet seat in public
T F 4. It would bother me to see a rat run across my path.
T F 5. I think it is immoral to seek sexual pleasure from animals.
T F 6. If I see someone vomit, it make me sick to my stomach.
T F 7. I might be willing to try eating monkey meat, under some
T F 8. It would bother me to see a human hand preserved in a jar.
T F 9. It would bother me tremendously to touch a dead body.
T F 10.I probably would not go to my favorite restaurant if I found out that
the cook had a cold.
T F 11. It bothers me to hear someone clear a mucuousy-throat.
T F 12. It would bother me to sleeping a nice hotel room if I knew that a
man had died of a heart attack in that room the night before.
SCORING: Count the number of Fs you circled on questions 2 and 7 and the
number of Ts circled elsewhere. The average score for U.S. males is five;
for females, seven. A higher score means you're more sensitive than average
I have a different set of rules, and I measure "squeamishness" along this
||You don't gag while changing a
nasty-bad poopy diaper.
||You can watch yourself getting an
||You can watch someone stitch-up your
||You can clean and gut a fish
||You can watch Apocalypto without
averting your gaze
||You can clean and gut a mammal
||You can eat trout with the
Overcoming the cultural revulsion response
A major task of Veterinary schools is helping the medical students overcome
their revulsion instinct, and their "anti-squeamish" training is legendary.
More than any other profession, an animal vet will regularly treat decaying body
parts and festering wounds with maggots.
People from China tell me that the find "Blue cheese" as repulsive, but they
have no problem eating rats. Americans have general revulsion to eating
any invertebrate or reptile foods and foods from other cultures are consider
- Iceland - rotting shark
- Mexico - Placenta stew, a treat where the family eats the new
- The Philippines - Balut, embryonic chicks, complete with
feathers, beaks and toes.
the Lowest of the Low: Neuroimaging Responses to Extreme Out-Groups,
Harris and Fiske, 2006, Psychological Science
The Anatomy of
Disgust: Book by William Ian Miller