Placebos and Positive Effects in Cognitive Training Studies

Guest Post by Kayt Sukel


There are few topics in the neuroscience world that can spark instant debate—but “brain games,” or computer programs or training products that promise to help improve cognitive skills like memory and attention, is definitely one of them. Over the past two years:

It’s likely this debate will continue for some time, especially now that a new study, published in the Proceedings of the National Academy of Sciences (PNAS), has demonstrated a strong placebo effect after a brief cognitive training program.

The idea that cognitive training regimens might be tainted by placebo effects is not a new one. In 2013, Walter Boot, a psychologist at Florida State University, and colleagues published a paper in Perspectives in Psychological Science illustrating that expectation effects can and do occur in video game training studies. He also referenced the lack of control for placebo effects in his 2014 Cerebrum article written with Arthur Kramer, “The Brain Games Conundrum:  Does Cognitive Training Really Sharpen the Mind?

“There’s some history here. A lot of studies in the video game literature have compared fast-paced action video games to slower and simpler games like Tetris or the Sims,” he says. “There, it seemed clear that these two interventions, the treatment and the control conditions, were so different that there was a strong possibility that expectations would be different as a result of these different type of interventions. And that’s what got me thinking about expectation placebo effects in cognitive training. It’s not hard to see how the different experimental groups might have different expectations that could affect performance.”

Pamela Greenwood, an applied cognitive psychologist at George Mason University, has been working towards the “holy grail” of cognitive training:  reliable transfer of skills beyond the training paradigm. But she says that it’s difficult to see whether transfer has occurred because of potential placebo effects.

“It’s hotly debated. And because of the way studies are conducted, it’s hard to know whether there is a placebo effect or real effect,” she says. “So we wanted to see if we could actually create a placebo effect instead of trying to tease it out later. We were surprised, actually, at how easy it was to do.”

For the newly published study, Greenwood and colleagues used two different methods to recruit participants. Half the participants were recruited with a flyer that explicitly said “brain training,” the other with one that did not mention “brain training.”  All participants were given an IQ test, a sham brain training task, and then a second IQ test. Those who had been recruited with the “brain training” flyer showed a significant increase in IQ, to the tune of 5-10 IQ points, after the sham task. There was no effect in the group that had a neutral flyer.

“Studies that have found positive effects don’t know how much of that is placebo. It’s a problem—and it’s one that’s been out there for a long time. We just decided to address it directly,” she says. “Of course, we haven’t really answered all of the questions. We need to do a lot more research to understand these effects and how that can improve training.”

PositScience’s Merzenich says that dozens of randomized controlled trials have found that different training paradigms drive “positive, enduring, generalized effects in behavior—when it has been looked for, in brains.”  He emphasizes that neuroscience-based and psychological-inspired forms of brain training are different animals. And he argues that studies subjected to placebo effect criticisms fall into the psychology-inspired class. “Tearing something down is a lot more fun than building something up,” he says.

But Greenwood says she has no intention to tear anything down. She sincerely hopes no one reads this study and concludes that cognitive training is a waste of time.

“Older people undergoing cognitive decline—that’s a big problem. Children who cannot learn—that’s a big problem. I don’t want anyone to drop their hands and say, ‘Cognitive training is all just a waste of time,’” she says. “But I do hope that people come away from this paper and are inspired to design their studies better. I hope that it actually helps us better design our trainings. We just need to go back to the drawing board a bit and try to figure out the best way to help make people smarter.”

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