Explain xkcd: It's 'cause you're dumb.
Revision as of 09:44, 12 August 2012
Welcome to the explain xkcd wiki!
We already have 11 comic explanations!
(But there are still 1577 to go. Come and add yours!)
Go to this comic
Title text: My MRI research shows a clear correlation between the size of the parietal lobe--the part of the brain that handles spatial reasoning--and enjoyment of 3D Doritos®.
|| This explanation may be incomplete or incorrect: Quick attempt; needs links and real examples, as well as summarizing/editing.|
Reductionism is the belief that things can be explained by their smaller parts. It can be abused, when complex phenomena with multiple causes are attributed to a single, simple cause.
Neurological reductionism is the attempt to explain people's behavior and personality by physical features of their brain. With advances in neuroscience, and especially in brain imaging, there's a fad to claim that brain types determine what the mind is. Examples of this kind of bad reductionism would be:
- Male brains have more grey matter than females. Therefore males are smarter. For an example of criticism of this kind of reasoning, see Male and female brains: the REAL differences (4 December 2013).
- Brains of gay males are slightly more symmetrical, as are female brains, when compared to straight males. Therefore gay men are fated to be more effeminate.
- The left side of the brain is associated with logical thinking, and the right, with visual and artistic thinking. Therefore people divide into "left-brain" or "right-brain" types, depending on how good they are at using each side.
There are several problems with this kind of reasoning. First, most studies identify correlation, not causation. Brains are plastic; they can be shaped by experience. For example, if, in a given society, the females are taught to mind their appearance, and the males are taught that aesthetic considerations are unmanly, then of course the female brains will end up with more developed aesthetic centers. In other words, behavior and capabilities aren't always determined by the brain. Sometimes it's the behavior that shapes the brain; sometimes a third factor (e.g. malnutrition) shapes both.
Second, even when the brain is actually a cause of the behavior, it's far from the only piece in the puzzle. Many studies on brain differences are correlation studies, often about very small effect sizes. Unfortunately the popular science media tends to gloss over the statistical concept of "effect size". For example, imagine a study that says that male-type brains have more attention-deficit disorder (ADHD). Journalists are prone to report it simply as "STUDY SHOWS THAT MALES HAVE MORE ADHD", and this becomes a conversation soundbite. But what if the study found that males are merely 0.01% more likely to have ADHD than females (a small effect size)? This effect would be a lot less important than, say, genetics, or pregnancy smoking.
Another kind of excessive neuronal reductionism is the overemphasis on brain modules ("scientists identify brain area responsible for religious faith", and the like). Though it's true that the brain has specialized areas, it's also true that the processing is very complex, messy, and distributed all over. Some varieties of brain damage can often be overcome by learning to use undamaged areas of the brain.
The comic illustrates the problem by analogy to some better-understood general-purpose computing hardware: the CPU in a smartphone. Cueball and Megan have used their phones to take pictures of the same event: a triathlon, that is, an athletic competition comprising three modalities (e.g. swimming, cycling, and running). Cueball wonders why is it that Megan's photos are more popular. Megan gives a reductionist explanation (starting with the typical "research shows that"): Cueball's phone only has two cores. In a CPU each core is, roughly speaking, capable of acting as an independent computer. Megan thinks that this means Cueball's smartphone can only capture two events at the same time. She misunderstoods how the specialized modules work; the number of cores is unrelated to how many events can be captured. This is like saying that male brains are better at spatial reasoning, and therefore males are better photographers.
A CPU with more cores could process pictures faster, speeding up facial recognition or color filters. So it's true that Megan's CPU makes it slightly easier for her to take pictures. However, this has, at best, a very small effect in the number of "likes". There's a lot more going on with photography than the GPU of the phone: Megan's photographing skills, her luck in capturing interesting scenes, the number of online friends she has, etc.
So Megan misunderstands: the modularity of CPUs; the small effect of the CPU on the quality of her photography; and the actual causes of her success, much like people who reduce ability to brain advantages.
The title text is mocking reductionist explanations based on magnetic resonance brain imaging. One of the most famous (and disputed) claims about gendered brains is that women's brains are (slightly) worse at spatial reasoning. In the title text, a larger spatial reasoning brain area is associated with enjoyment of 3D Doritos® – a three-dimensional variation of the popular junk-food snack.
- [Cueball hold his smartphone looking at it while talking to Megan who is holding her smartphone in her hand.]
- Cueball: Your photos from the triatholon got so many more likes than mine.
- Megan: Yeah - My phone is quad-core. Research shows that iPhones like yours have just two cores, so they have a hard time capturing scenes with three different events in them.
- [Caption below the frame:]
- If we talked about phone hardware the way we talk about brain hardware
- There is a spelling error in Cueball's comment where he says triatholon instead of triathlon. (Maybe it will be corrected by Randall when he notices?)
Feel free to sign up for an account and contribute to the explain xkcd wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an xkcd web comic, it should be here.
- List of all comics contains a complete table of all xkcd comics so far and the corresponding explanations. The red links (like this) are missing explanations. Feel free to help out by creating them!
Don't be a jerk. There are a lot of comics that don't have set in stone explanations, feel free to put multiple interpretations in the wiki page for each comic.
If you want to talk about a specific comic, use its discussion page.
Please only submit material directly related to—and helping everyone better understand—xkcd... and of course only submit material that can legally be posted (and freely edited.) Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users posting such are at risk of being blocked.
If you need assistance from an admin, feel free to leave a message on their personal discussion page. The list of admins is here.
Explain xkcd logo courtesy of User:Alek2407.