Tuesday, September 22, 2009

Bad pun, but interesting article

Normally, there is nothing that turns me away from an article faster than a pun in the headline, but for once, curiosity got the better of me when I came across this Wired article.

Scanning Dead Salmon in fMRI Machine Highlights Risk of Red Herrings

Neuroscientist Craig Bennett purchased a whole Atlantic salmon, took it to a lab at Dartmouth, and put it into an fMRI machine used to study the brain. The beautiful fish was to be the lab’s test object as they worked out some new methods.

So, as the fish sat in the scanner, they showed it “a series of photographs depicting human individuals in social situations.” To maintain the rigor of the protocol (and perhaps because it was hilarious), the salmon, just like a human test subject, “was asked to determine what emotion the individual in the photo must have been experiencing.”

The salmon, as Bennett’s poster on the test dryly notes, “was not alive at the time of scanning.”

If that were all that had occurred, the salmon scanning would simply live on in Dartmouth lore as a “crowning achievement in terms of ridiculous objects to scan.” But the fish had a surprise in store. When they got around to analyzing the voxel (think: 3-D or “volumetric” pixel) data, the voxels representing the area where the salmon’s tiny brain sat showed evidence of activity. In the fMRI scan, it looked like the dead salmon was actually thinking about the pictures it had been shown.

The article is about the perils of false positives when using fMRI machines, and raises the question whether we can trust the results from such scanning. This question is hard to answer, but the answer is probably "it depends". The trustworthiness of such results depends on the rigorousness of the statistical methods used.

One things this experiment also highlights, which I believe strongly in, is that one should not just test for whether things works when you expect it to work, but also that it fails to work when it's expected to not work. This is something I preach when making IT systems, and it is something which everyone who do any type of tests or measurements should keep in mind.

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