Dermatology Quiz: Answers

The first statement on yesterday’s quiz was true. Because Americans sit on the left side of the car when they drive, if they drive a lot they get more UV light to the left of their faces than the right. Therefore, they get more left-sided skin cancer. This picture of a truck driver, linked in yesterday’s comments, provides a good demonstrations of the effect of UV on skin:

On the other hand, you probably shouldn’t avoid sun exposure entirely, since it seems to protect against cancer – I previously was skeptical of a Vitamin D/cancer link, but sun exposure might operate through Vitamin D-independent pathways.

The second statement was false. At least, it was supposed to be. I tried to invent a distractor answer I was pretty sure was false. Commenter Kolya came up with a really sneaky argument for why it might be true. This just goes to show how easy it is to confound something. Please be reassured that I am not really that tricky.

The third statement was true. See Treatment of depression with onabotulinumtoxin A: a randomized, double-blind, placebo-controlled trial. 52% of botox group responded to treatment vs. 15% of the placebo group (who got injected with nothing; sucks to be them) with effect lasting at least six weeks.

The likely explanation is the “facial feedback hypothesis”, which posits that the brain uses facial musculature as a sort of “notepad” for emotions – if one part of the brain decides to feel happy, it makes the face smile, and then other parts of the brain can check whether the face is smiling a couple minutes later and figure out if they are supposed to be feeling happy. As silly as it sounds, if you paralyze the muscles that frown, that makes it harder to feel sad. Even better, the same treatment improves mood in healthy people without depression.

I actually didn’t realize that last part until I started writing this post. I wonder if the Botox effect is susceptible to happiness set point or not. I could easily see it not being so, which would make it one of the most powerful happiness-boosting interventions that exists and a little less creepy than giving your usual oral or IV drugs to make people happier.

Botox costs $400 a pop and lasts for months. I wonder how that compares to poverty relief, health care, and malaria nets in the utilitarian calculus.

Darnit, just once I want to learn an interesting medical fact that doesn’t end up as a plan to drug the entire population.

(but think how pretty everyone would be!)

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29 Responses to Dermatology Quiz: Answers

  1. Doug S. says:

    I’m reminded of one of Eliezer’s favorite examples of poorly implemented utility functions, in which an AI that you tell to get people to smile (because smiling people are happy) instead does something to people’s faces so they can’t change their facial expressions, resulting in a bunch of very annoyed smiling people…

  2. Pingback: The Appearances and The Things Themselves | Benjamin Ross Hoffman's personal blog

  3. Benquo says:


    I’m updating thusly:

    1) I was correct to look for statistical mechanisms rather than causal ones. I will do more of this in the future.

    2) I was incorrect to assume Scott was doing the same, or to look exclusively for statistical artifacts. Some things really do cause others. I will not be so ready to discard plausible causal mechanisms entirely when a smartass statistical answer becomes available.

    3) I was incorrect to assume that the possibilities allowed by the quiz question were exhaustive. Next time Scott posts a quiz I will not ignore possible smartass answers that assume the question is incorrect. I should explictly consider these as possibilities, and assign them probabilities.

    4) Wow, that trucker face thing isn’t just an urban legend / misleadingly described picture? Interesting. I will cease feeling bad about applying sunscreen to my face, though I will be more willing to engage in whole-body sun exposure because of the “sunlight prevents cancer” thing. (Just kidding – it’s not worth it because it’s sure to cause me to feel bored out of my mind, very unpleasantly self-conscious about my body, or both. But now at least I know this is killing me!)

  4. adbge says:

    It’s not just botox. From one of my earlier posts:

    Ohlsen, Ponten, and Hamburt (1978) noted that twenty-five of seventy-one women in their study were receiving psychiatric treatment prior to a breast augmentation procedure, whereas only three continued to do so after the operation.1 Klassen and his colleagues (1996) also found substantial reductions in psychiatric symptomatology among people receiving plastic surgery.2 Cole and his colleagues (1994) reported that 73 percent of their patients reported a higher quality of life after cosmetic surgery, compared to only 6 percent who reported a lower quality of life.3 The largest gains were for cosmetic breast surgery (both reductions and enlargements), with slightly smaller gains for abdominoplasty (tummy tucks) and only slight gains for rhinoplasty (nose jobs).

    And from the paper “Life Goals Matter to Happiness: A Revision of Set-Point Theory”:

    Entertainingly, the only positive life event which has been unambiguously shown to raise the SWB set-point is cosmetic surgery (Wengle, 1986; Loewenstein and Frederick, 1999).

    • Ialdabaoth says:

      Entertainingly, the only positive life event which has been unambiguously shown to raise the SWB set-point is cosmetic surgery (Wengle, 1986; Loewenstein and Frederick, 1999).

      My personal theory:
      The well-being “set point” is actually not fundamental to a person, but is reinforced by their social environment based on their status. I.e., given someone’s perceived status, we decide subconsciously that they should have a certain level of happiness compared to those around them. Then, we inflict suffering upon them when they rise above that, and offer help when they drop below it. Everyone does this in incredibly subtle and interacting ways, which make it hard to pin down specific instances for further study.

      Maybe more money doesn’t help because it doesn’t come with a corresponding increase in relative status the way changing your appearance does? Or maybe the fact that more money doesn’t help falsifies the entire premise. I’ll have to think of some good studies that would test this better.

      • yli says:

        Also there’s disability which is not supposed to permanently move your set point either. But it’s hard to imagine that becoming disabled would leave your status exactly where it was before, however status is defined.

    • ThrustVectoring says:

      I’d tentatively add LASIK as a candidate. It’s unambiguously made my life better.

    • yli says:

      Another well known fact about the happiness set point is that if you get into an accident and become disabled, it returns to baseline a few months later. So here’s a recipe for infinite happiness:

      1. Get into an accident which disfigures you.
      2. Wait for your happiness to return to normal levels.
      3. Fix your appearance with plastic surgery.
      4. Gain a permanent boost to your happiness set point.
      5. Repeat.

      It may not work when the accidents are deliberately self-inflicted though. In that case there’s an opportunity for some altruistic action.

      • Zathille says:

        Still, since a negative change in appearance had but a temporary effect on happiness, why would a positive change be permanent? Is there an additional mechanism at work here which causes such a phenomena to be asymmetrical in this sense?

        • US says:

          I don’t have a direct answer to your question, but for what it’s worth it seems to me that if there’s an asymmetry here the permanent effect may be more likely to be the negative one than the positive one:

          “Apparently, most of the specific events that happen to us have only temporary effects on happiness. Within 3 months of even rather drastic incidents, such as breaking a leg or winning the lottery, we tend to return to pretty much the same level (Suh et al. 1996). […] negative experiences are associated with more intense and lasting emotional reactions than positive experiences (Fredrickson and Losada 2005), presumably because a single threat can have a far more drastic effect on genetic fitness (e.g., leading to death), than can a single fortunate event.”

          The quote is from The Biology of Happiness, by Bjørn Grinde (I incidentally do not recommend the book).

          Incidentally on a more general note the fact that facial expressions and related stuff matters in terms of happiness is not a new idea – here’s another relevant quote from the book:

          “One example concerns a study that asked students to keep a pencil either between the lips or between the teeth while reading cartoons (Strack et al. 1988). Those with the pencil between the teeth subsequently rated the cartoons as more funny. By having the pencil in the teeth, they forced the lips into a smile (without knowing it). Presumably the smile muscles send signals to the brain saying that the mood is good, which is sufficient to have an impact on the actual mood […] Likewise, forcing laughter (Shahidi et al. 2011), or blocking a frown (Lewis and Bowler 2009), appears to be sufficient to boost happiness. These studies suggest that our emotions are reinforced—perhaps to some extent even driven—by their corresponding (facial) expressions”

  5. Anonymous says:

    Damnit, quick self-experiments on forcing a big smile for a minute are showing a bigger effect than my sanity would like. I’m really mad at my neural circuitry, but there’s also a wide euphoria behind (not behind as in causing, except, well, that too) that emotion.

    Unhappiness is the proper response to my current situation, damnit! Pay attention to me, me, not my face!

  6. Will says:

    Seems more creepy than drugs to me.

  7. Michael Keenan says:

    I thought the acne thing was true because women and white people get more acne and live longer than most other genders and races (at least in America).

  8. Daniel says:

    This says men get acne more than women:

    Oops! Sorry, this was meant to be a reply to Michael Keenan above.

  9. naath says:

    If the thing about skin cancer is true then presumably people in the UK who drive a lot get a lot more right-side cancer because we drive on the other side; if they don’t then I guess it’s not to do with driving…

    • Anonymous says:

      It’s about driving with the roof or at least driver side window open. I would expect to see a bigger effect further south then England.

      • Anonymous says:

        Driver side windows are not treated to block UVA. They don’t have to be open for there to be damage (but if they are open, there will also be UVB).

    • Raoul says:

      I don’t know of any studies relating to the UK, but I have found one for Australia:

      Men (taller, generally drivers) were more likely to have skin damage on their right arm than on their left arm, while women (shorter, historically more often passengers) were more likely to have skin damage on the left side of their face than on the right side.

  10. AG says:

    Well, I’m going to try habituating myself into smiling all the time.

    Or I could buy some chopsticks:

    Participants (N = 170) naive to the purpose of the study completed two different stressful tasks while holding chopsticks in their mouths in a manner that produced a Duchenne smile, a standard smile, or a neutral expression. Awareness was manipulated by explicitly asking half of all participants in the smiling groups to smile (and giving the other half no instructions related to smiling). Findings revealed that all smiling participants, regardless of whether they were aware of smiling, had lower heart rates during stress recovery than the neutral group did, with a slight advantage for those with Duchenne smiles.

    Probably cheaper than botox, though not necessarily less creepy.

  11. ElrondHubbard says:

    A while ago I underwent the treatment for chronic, severe migraine, which is dozens of botox injections in the head, face and neck. Since then I’ve felt a persistent wonderful Zen calm and peacefulness. I suspect now that this is because my face and neck have been so damned relaxed.

  12. Anonymous says:

    So the evidence for #1 consists of a picture of one guy from the internet? How about a reference for the statistic? Are there enough truckers/long-distance-drivers to justify “significantly more Americans”?

    Since botox is a paralytic normally applied to prevent smiling induced winkles and keep the face neutral, not lock it into a smile, shouldn’t normal botox users experience more depression under the facial feedback hypothesis? The first study seems seriously confounded by the so-called placebo group being easily able to tell that they were given a placebo injection. Given this, the main effect could be placebo (especially with the low bar of 50% improvement). Not that I doubt the hypothesis; this just doesn’t seem like good evidence, certainly not good enough to recommend injecting toxins into people’s faces, depressed or otherwise. Some new age treatment, like laughter yoga, would be cheaper, easier, and probably more effective.

  13. Mary says:

    I observe that fair skin is associated with acne, and more severe acne — and also socioeconomic status. Which could also lengthen lives.

  14. Jeff says:

    This makes me think I might genuinely be happier overall because I cannot physically get my facial muscles to make a frown.