Most studies linking features in brain imaging to traits such as cognitive abilities are too small to be reliable, argues a controversial analysis.
A scan using functional magnetic resonance imaging, or fMRI, shows areas of the brain active during speech.to a journal that focuses on child development. Previous studies had shown that differences in brain function between children were linked with performance in intelligence tests. So Marek decided to examine this trend in 2,000 kids.
“There’s a lot of investigators who have committed their careers to doing the kind of science that this paper says is basically junk,” says Russell Poldrack, a cognitive neuroscientist at Stanford University in California, who was one of the paper’s peer reviewers. “It really forces a rethink.” The researchers then used subsets drawn from these large databases to simulate billions of smaller studies. These analyses looked for associations between MRI scans and various cognitive, behavioural and demographic traits, in samples ranging from 25 people to more than 32,000.
For brain imaging, Marek says, “I don’t know if we need hundreds of thousands or millions. But thousands is a safe bet.”