Brain training may be harmful to some aspects of memory performance

Much attention has been focused recently on whether brain training programmes have the far-reaching benefits claimed by their commercial purveyors. Brain training usually involves completing exercises on computer to strengthen your working memory – essentially your ability to hold in mind and process multiple items of information at once ("cognitive training" would be a more apt name). The argument put forward by brain training companies like Lumosity and Posit Science, is that working memory is such a fundamental mental process that if you boost your working memory capacity through training, then you will experience wide-ranging benefits, even in ostensibly unrelated activities, such as in your performance at work. However, a comprehensive review published earlier this year concluded that there is in fact inadequate evidence to justify such bold claims. Now a study in Memory and Cognition brings even worse news for brain training enthusiasts – compared to control conditions, working memory training was actually found to worsen performance on a test of recognition memory.

Laura Matzen and her colleagues recruited 86 male and female participants (average age 37), all employees at the Sandia National Laboratories in Albuquerque, New Mexico. In the first week of the study, the researchers tested the participants' baseline performance on recognition memory (the ability to study several dozen words, one at a time, and then judge in a subsequent test which words they'd seen and which were new); and on verbal and spatial working memory (this involved recalling sequences of symbols while also judging whether sentences made sense or not, and the spatial version involved remembering the order and location of shapes in a grid).

The next three weeks were spent training. Some of the participants were allocated to working memory training, which involved spending half an hour a day, four days a week, on a version of the n-back task (the kind of task that features in many brain-training programmes). Participants had to look at streams of letters on a screen and look out for whenever the current item was the same as the one a certain number (n) of items earlier. The better participants performed, the harder the task became by requiring they attend to earlier items in the sequence. Other participants were allocated to three weekly sessions of mental imagery training, in which they were taught, and practised, converting to-be-remembered words into memorable images. Finally, the remainder of the participants were allocated to a no-training control condition.

During the fifth and final week of the study, all participants repeated the original baseline tests of working memory and recognition memory, and the researchers compared the participants' performance with their earlier baseline. The researchers also asked participants about what learning strategies they'd used in these final tests, if any, such as mental rehearsal of to-be-remembered words or imagery techniques.

All the participants showed improvement in the later test of working memory, but this improvement was no greater in the working memory training group compared with the other groups, which means there was no evidence that working memory training had any specific benefits on working memory performance. But arguably more worrying still for brain training advocates is that whereas the control group showed equal performance on the later recognition memory test compared with baseline, and the imagery training group showed improvements compared with baseline, the working memory training group actually deteriorated in their recognition memory performance.

Why would working memory training worsen recognition memory performance? Some clues come from the participants' comments about their use of strategies – those in the working memory training group were more likely than others to say they used a "shallow" strategy such as simple mental repetition (not very effective when studying dozens of words), or no strategy at all. The researchers speculated that perhaps the experience of working memory training discourages us from using effective strategies, maybe because it encourages a confidence in and reliance on one's basic memory processes.

A potential criticism of the study is that the working memory training was much more time consuming that the mental imagery training, potentially leaving the participants in the working memory condition more tired and demotivated by the time of the final tests. However, there was little evidence to support this interpretation – for example, drop out from the study was no greater in the working memory condition than other groups, and remember participants who completed the working memory training showed comparable performance to others on the final tests of working memory.

This is just one study with a relatively small sample and it only used one kind of test to measure recognition memory performance, so it shouldn't be treated as decisive evidence. However, Matzen and her team said their findings are worrying because recognition memory performance is so important to many real-life challenges, especially in educational settings. "The results present a cautionary tale about unintended consequences arising from cognitive training," they said. "Even if participants improve on the trained task, the training may impact their performance on untrained tasks in unforeseen ways."

Further reading

—Practice makes imperfect: Working memory training can harm recognition memory performance