14 DAY TRIAL // Last week, scientific bloggers had a field day with a report showing that a dead salmon's brain was able to light up under a functional Magnetic Resonance Imaging (fMRI) machine, when shown pictures of humans. While some were quick to point out that this was proof of an ethereal soul, and others said that the dish was still “thinking” after death, researchers who made the report public say that neither is the case. Rather, they argue, this study was done as a reminder to colleagues in the scientific community of the dangers accompanying fMRI-survey interpretation, LiveScience reports.
fMRI technology allows experts to essentially keep track of blood-flow patterns inside the brain. While this is an extremely useful ability for scientific studies, it can also lead to a number of “false positive” results that can taint the investigation. Misleading results, published in important journals, can also influence policymakers, and perpetuate changes that are, in fact, negative to the very people they were supposed to serve. The results of the new investigation, showcased at a scientific conference earlier this year, show that the fish's brain did not behave in any abnormal ways, and that its actions can be thoroughly explained scientifically.
“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,” University of California in Santa Barbara (UCSB) Department of Psychology postdoctoral researcher Craig Bennett, who has also been the leader of the study, explains. Speaking of the actual fish, he adds, “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. By far it was our crowning achievement in terms of ridiculous objects to scan,” the expert says. After he and his team conducted the first study on dead salmon, back in 2005, he started believing that false positive results might have been at work. In 2008, once the necessary statistical tools had been developed, he ran the earlier results through them, and discovered not one, but three false positives.
The scientist adds that, while reviewing comments about his team's work, he came across one that best described the situation. “The recorded signal is changing due to noise. The point of the experiment is that if you look at enough signals, the noise in one will match the timing of your experimental stimulus, purely out of chance.”