Dead Salmon Tell No Tales

It’s a study that serves to remind everyone who generates or tries to make sense of scientific data to be wary of misleading measurements, false positives and just plain noise: no, that dead salmon that brain researchers subjected to brain scanning technologies did not actually respond when shown different photographs of people.

Functional magnetic resonance imaging (fMRI) is an invaluable tool for providing detailed neurological analysis in a noninvasive, radiation-free manner. But University of California Santa Barbara postdoctoral researcher Craig Bennett’s recent tongue-in-cheek experimentation highlights the need to be on the lookout for misleading results.

As described in an article at LiveScience, the cautionary tale begins to unfold back in 2005. Bennett and his graduate student colleagues at Dartmouth College purchased their 3.8-pound test subject at a local fish counter, brought it back to the lab, hooked it up to the fMRI, showed the fish different photographs of people and monitored the results (previous investigations by Bennett and team involved applying similar procedures to a dead bird and to a pumpkin). LiveScience quotes Bennett’s technical poster presenting his findings:

"The salmon was approximately 18 inches long, weighed 3.8 lbs, and was not alive at the time of scanning. The salmon was shown a series of photographs depicting human individuals in social situations with a specified emotional valence. The salmon was asked to determine what emotion the individual in the photo must have been experiencing."

Analysis of the fMRI data from the fish produced what appeared to be positive results, but which were actually false positives.

Bennett recently presented his findings at a June brain mapping conference in San Francisco. And while several conference material reviewers initially thought that they were being geek-punked, they were ultimately convinced of the stone-faced seriousness at the basis of Bennett’s paper.

Photo courtesy of U.S. Department of Energy, via Wikimedia Commons