Working with Helena Westerberg, then a doctoral candidate student in psychology, Klingberg assembled a small sample of fourteen children who would each complete a set number of computerized training exercises several days a week for five weeks. They decided that the study would include only children with ADHD because that population tends to exhibit pronounced working memory problems and any improvements due to training would likely be more visible.
On the first day following the pilot study, Westerberg, who was blind as to which students belonged in the control group, was conducting post training tests when she came across some remarkable results. She noticed that some of the students had dramatically increased their ability to recall information.
“I remember very clearly that Helena was blown away on the very first day,” says Klingberg. “And I think that was the first time it occurred to me that we may have hit on something very important.”
Their enthusiasm increased as the remaining data was collected and analyzed. The results showed that the training had substantially impacted the working memory capacitates of those children in the treatment group.
“We were very surprised and immediately saw that this would have big implications, not just for people with ADHD but for any number of people who are held back by working memory capacity,” says Klingberg.
Klingberg immediately began a second and more ambitious study. It was conducted at multiple sites in Sweden using the gold standard in scientific research: a randomized, double-blind, controlled design. Users were divided into two groups, one using working memory training, the other using a placebo program. Working memory and other executive functions were measured before, immediately after and three months after training, as were parent and teacher ratings of ADHD symptoms. The results were clear – the training worked.
The study was eventully published in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP) – and drew the attention of some of the world’s leading researchers and experts.
“There was a lot of skepticism after our first study, because people really thought working memory was a fixed characteristic – I even had my doubts,” says Klingberg. “But when the second study was released, it truly challenged that notion.”