Individual studies of the topic show different, and sometime contradictory, results, and as one meta study puts it,[1] asking the question “Does cognitive training improve intelligence?” is as inappropriate as asking “Does medicine cure disease?”, since none of them specify which particular intervention (which medicine or working memory training program) is being evaluated, for alleviating which condition is it applied (ADHD, stroke, general cognitive improvement etc.
[3] Since then, a range of additional clinical experiments have been completed, with larger sample sizes, clearly defined control groups, and more uniform treatment of outcome variables.
[12] Working memory capacity is usually assessed by determining the number of pieces of information that a person can hold in their mind at once.
Numerous scientific studies have linked working memory capacity with strength in other fundamental cognitive abilities, including attention and intelligence.
[14][15] Conversely, poor working memory is assumed to be one of the core deficits in ADHD as well as a number of learning disabilities.
[18] Computers are additionally programmed to adjust the difficulty of the task to the individual's performance with each trial in order to maximize learning and overall improvement.
[21] Common strategies used in working memory training include repetition of the tasks, giving feedback such as tips to improve one's performance to both the parents and the individual, positive reinforcement from those conducting the study as well as parents through praise and rewarding,[18] and the gradual adjustment of the task difficulty from trial to trial.
By using tasks that differ from ones in the study, laboratory results can demonstrate transfer effects if high scores are achieved, since these were not learned during training.
A trial study tested the WM of 733 adolescent participants, randomly assigning them to an active or placebo emotional working memory training.
After 4 weeks of bi-weekly training, results showed improvements in working memory, both short-term and long-term emotional functioning, and even an increase in self esteem among the active group.
While improvements in WM were observed in both groups, there were many limitations and further research is still needed to produce training that will create long term effects in those who suffer from mental health disorders such as anxiety and depression.
[31] A few years after this paper was published, a randomized, placebo-controlled study was conducted to test the transfer effects of working memory training while controlling for all aspects previously mentioned.
[32] For instance, in one case, a college student practiced repeating numbers that were read to him aloud for an hour each day.
This study and others like it contributed to the prevailing assumption in the scientific community that working memory is a set characteristic that cannot be improved.
Many clinical studies published in 1990s and 2000s claim that working memory training is an efficient strategy for mitigating effects of ADHD and other cognitive disorders.
By this time, some twenty-three studies met these criteria, including both clinical samples of typically developing children and adults.
While the results were conclusive for ADHD population, there was no convincing evidence for transfer or generalization effects (indicating improved capacity) in typically developing children and healthy adults.
Moreover, research at the Wallenberg Neuroscience Center in Sweden indicates that working memory training may decrease hippocampal neurogenesis.
The report suggests that increased stress, caused by an intense training of working memory, can reduce the production of hippocampal neurons.