Want to improve your memory, focus and cognitive abilities? Download any of the leading brain training apps, and you'll be well on your way in just a few minutes a day. Or so they claim.

Apps like Lumosity, BrainHQ and CogniFit seem too good to be true. Even though these apps frequently cite science as evidence, it's important to remember that all science is not necessarily good science.

Now there's even less reason to believe the effectiveness of brain training products. A group of University of Illinois psychologists reviewed all the scientific papers that brain training companies use to market the proven success of their brain training apps and games.

The seven psychologists spent two years reviewing 374 papers total. The group just published their findings in the Psychological Science in the Public Interest, and here's what they found:

Based on this examination, we find extensive evidence that brain-training interventions improve performance on the trained tasks, less evidence that such interventions improve performance on closely related tasks, and little evidence that training enhances performance on distantly related tasks or that training improves everyday cognitive performance.

In other words, these brain training games do help you improve -- but only at playing that game. These games don't, the psychologists state, help your brain improve at much else.

For example, you might get really good at finding words in scrambled letters, matching shapes or calculating simple math in falling raindrops. But that doesn't mean your vocabulary is improving, you're better at remembering where you've placed your keys, or can think more quickly.

The following are claims from leading brain training products that these psychologists are calling into question:

  • Lumosity claims its games help improve memory, attention and problem solving
  • AARP and Posit Science created a suite of BrainHQ games that claim to help people stay sharp as they age
  • Cogmed is a brain training program that claims to help people improve focus and excel academically, socially, and professionally
  • CogniFit claims its games train your memory, concentration and other cognitive skills

In many of the 374 brain science papers, the reviewers found the subjects knew what was being studied. This implicitly leads to bias. It's the same reason the power pose was brought into question by one its original researchers. If participants know what the expected hypothesis is -- that playing brain science games improves your memory or that standing in a power pose improves your confidence -- they're more likely to skew the results in the favor of that hypothesis.

Other problems with the brain training research included a lack of control groups, exaggeration of results, or the studies being too small to produce statistically significant results. In an Atlantic article, Neuroscientist Dorothy Bishop points out these games are solitary activities. She says your brain benefits more from an activity that's both socially engaging and stimulating, such as learning a foreign language.