The salmon had likely been dead for days, purchased at a local fish market and placed in an MRI scanner by scientists who then paraded photographs of people in front of its blank eyes. Later, researchers found that the results indicated brain activity, as if the fish was reacting from beyond the grave.
These results, revealed on a poster at the Human Brain Mapping conference in San Francisco last June, sparked claims by some bloggers that the fish was still thinking or that salmon have souls. The truth isn’t nearly so exciting.
"The goal of the salmon poster was to encourage the minority of researchers who report uncorrected statistics to move forward and begin using basic multiple comparisons correction in their research," says study leader Craig Bennett, a postdoctoral researcher in the Department of Psychology at the University of California, Santa Barbara.
Bennett and his colleagues at Dartmouth College studied the salmon as part of a project to develop MRI protocols, with previous subjects including a pumpkin and a dead bird.
"The salmon was approximately 18 inches long, weighed 3.8 lbs, and was not alive at the time of scanning," the team said in their poster presentation.
"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."
The findings, which were likely caused by noise that coincidentally matched up with the timing of the experimental stimuli, were submitted to a journal as a cautionary tale about data interpretation.
Using a dead salmon as a test subject was ludicrous — and that was the point.
"By far it was our crowning achievement in terms of ridiculous objects to scan," said Bennett.