But according to a new report, most intervention studies like these have a critical flaw: They do not adequately account for the placebo effect.
The new analysis appears in the journal Perspectives on Psychological Science.
The results of psychological interventions, like medical ones, must be compared to improvements in a control condition, said University of Illinois psychology professor Daniel Simons, who co-wrote the article with Walter Boot, Cary Stothart and Cassie Stutts, of Florida State University. In a clinical trial for a new drug, some participants receive a pill with the critical ingredients, and others receive an identical-looking pill that is inert – a placebo. Because participants cannot tell which they received, people in each condition should be equally likely to expect improvements.
In contrast, for most psychology interventions, participants know what's in their "pill," Simons said.
"It's not possible to use a brain-training program for 10 hours without knowing the type of training you received," he said. "People can form expectations for what will improve based on their experiences with the training tasks, and the existence of differences in expectations between people in treatment and control groups potentially undermines any claim that improvements were due to the treatment itself. Not one of the studies cited by the brain-training companies looks at differing expectations between the groups."
Merely having an "active control group," one that does something for the same amount of time as the treatment group, does not protect against the placebo effect, Simons said. A treatment group that completes an intensive memory-training regimen might expect improved performance on other cognitive tasks assessing memory. A control group that does crossword puzzles or watches DVDs for the same amount of time likely won't expect the same amount of improvement on the same tasks, he said.
"These problems are not limited to brain-training studies," Simons said. "They hold true for almost all intervention studies."
To illustrate the pervasiveness of this problem, the researchers examined expectations for improvement in studies of the effect of playing action video games on measures of perception and attention.
"Such studies find greater improvements in performance on attention and perception tasks after training with action video games than after training with non-action games for the same amount of time," Boot said. "However, even with this sort of active control condition, these interventions still are at risk for differential placebo effects."
The researchers measured expectations in two survey studies involving 200 participants each. Participants watched either a short video of an action game ("Unreal Tournament") or one of the games commonly used as controls in these studies ("Tetris" or "The Sims"). They then read descriptions of the cognitive tests used in the studies, watched short videos of the tests, and answered questions about whether they thought their performance on the tests would improve as a result of training on the video game they had viewed.
The results showed that expectations for improvement were greater for the action-game group than for the control games on exactly the same tests that showed bigger improvements for action-game training in the intervention studies. In fact, the pattern of expected improvements exactly matched actual improvements seen in video game intervention studies, the researchers found.
"If expectations for improvement align perfectly with the actual improvements, then any claim that the treatment was effective is premature," Simons said. "Researchers must first eliminate differences in expectations across conditions."
"Even though participants in psychology interventions typically know the nature of their intervention – you can't play a video game without knowing the game you're playing – there are steps researchers can take to ensure that the advantages of the treatment group are not due to expectations," Boot said.
For example, researchers can mislead participants as to the expected benefits of a particular intervention, giving those in the control group higher expectations for improvement than those in the treatment group. Researchers also can assess expectations generated by treatments in a separate sample of participants to ensure that expectations do not differ between intervention and control treatments.
"Although placebo effects can be helpful as well, we need to know what causes improvements in an intervention," Simons said. "We don't want to recommend new therapies, change school curricula, or encourage the elderly to buy brain-training games if the benefits are just due to expectations for improvement. Only by using better active controls that equate for expectations can we draw definitive conclusions about the effectiveness of any intervention."
Simons is an affiliate of the Beckman Institute for Advanced Science and Technology at Illinois.
Editor's notes: To reach Walter Boot, call 850-645-8734; email email@example.com.
The paper, "The Pervasive Problem with Placebos in Psychology: Why Active Control Groups are Not Sufficient to Rule out Placebo Effects," is available from the U. of I. News Bureau.
Daniel Simons | EurekAlert!
A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg
Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering