Main Page

Explain xkcd: It's 'cause you're dumb.
Revision as of 15:36, 20 March 2013 by Davidy22 (Talk | contribs)

Jump to: navigation, search

Welcome to the explain xkcd wiki!

We have collaboratively explained Expression error: Unrecognised punctuation character ",". xkcd comics, and only Expression error: Unrecognised punctuation character ",". (Expression error: Unrecognised punctuation character ",".%) remain. Add yours while there's a chance!

Latest comic

Go to this comic explanation

They also showed activation in the parts of the brain associated with exposure to dubious study methodology, concern about unremoved piercings, and exasperation with fMRI techs who won't stop talking about Warped Tour.
Title text: They also showed activation in the parts of the brain associated with exposure to dubious study methodology, concern about unremoved piercings, and exasperation with fMRI techs who won't stop talking about Warped Tour.


fMRI (Functional Magnetic Resonance Imaging), as the name suggests, is an offshoot of the MRI procedure. It is a technique designed to show brain activity, typically while the subject is performing tasks or responding to stimuli. During the test, the subject is laid in a relatively small cylinder inside a big, very loud, machine producing extremely strong magnetic fields. To prevent damage or injury, the subject must remove all metal objects from their body, including piercings, jewelry, watches etc.

In the tests shown, the brain activity detected is a direct result of the testing environment itself, and has nothing to do with the simple tasks being performed by the subject. During fMRI participants hear loud noises, are confined in a small space (thus the claustrophobia) and have removed their jewelry. The researcher has mistaken these associated brain activities as effects as being caused by performing simple memory tasks which the participants have been asked to do and not a direct result of the settings of the test. Thus, the brain areas described by Megan are those associated with taking a functional MRI scan, rather than those associated with the "test" supposedly being carried out.

In real experiments, reported activity patterns are always a result of subtracting average brain activity from many samples gathered during task from so called resting-state activity - which is obtained while subjects are not engaged in any task, thus eliminating the effect the setting has on brain activity. Apparently, the researcher in the comic has failed to account for that in the analysis of the data.

It appears that Randall makes fun of the overly confident, sweeping statements made by some fMRI researchers, often in the press. In reality the technique requires that the researcher account for several possible sources of errors by, among others, performing proper statistical analyses, multiple comparisons and using proper control groups. These are usually the reasons for fMRI criticism. See the link for further information, including a famous ironic study of a dead salmon which was shown various pictures of people while fMRI scans were made. The scans could be interpreted as showing meaningful brain activity, until the multiple comparisons problem was properly addressed.

The title text continues directly with this theme by saying that the subjects also showed activation in the parts of the brain associated with exposure to dubious study methodology. It then continues with the jewelry issue, now especially the concern about unremoved piercings. In the worst case these could be ripped off by the strong magnetic field. So it could be of some concern - especially when you take into consideration some of the places people may have piercings that is not obvious to the MRI personnel! The final remark about activation regards exasperation with fMRI techs who won't stop talking about Warped Tour. "Warped Tour" refers to a traveling music festival that has been going since 1995, originally as a punk rock festival, but now with a more diverse set of music. Due to the nature of Mosh Pits, the loud, cacophonous music, the facial jewelry of concert-goers and the tight quarters of the pit make it similar in description to an MRI.


[Megan talking to an unseen audience in front of an fMRI brain scan]
Megan: Our fMRI study found that subjects performing simple memory tasks showed activity in the parts of the brain associated with loud noises, claustrophobia, and the removal of jewelry.

Is this out of date? Clicking here will fix that.

New here?

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the 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! Here's how.


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 who repeatedly post such content will be 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.

Personal tools


It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal or Bitcoin?