Dr Darren Dunning: Ten Papers on Working Memory you should read
I’ve heard working memory training described as being like the ‘wild west’ of psychology. There seems to be two contrasting sides, one thinks that it represents an exciting new field of cognitive neuroscience that shows significant benefits in cognition for both children and adults while the other believes that these benefits do not extend beyond tasks that are closely related in structure to the trained tasks.
Both sides seem intent on shooting the other down, fortunately not literally.
So which side is right? The answer to that question is not simple. To try and help you decide which side of the fence you sit on, or maybe you sit slap bang in the middle, here are 10 papers on working memory training (presented in alphabetical order).
Chein, J.M., & Morrison, A.B. (2010). Expanding the mind’s workspace: Training and transfer effects with a complex working memory span task. Psychonomic Bulletin & Review. 2010, 17, 193-199.
A group of adults completed either working memory training or were untrained. Training consisted of practice on verbal and visual working memory tasks for four weeks. The trained group showed benefits in other, non-trained working memory tasks, a Stroop task (that measures inhibition) and a measure of reading comprehension. Chein and Morrison concluded that working memory training could be used as ‘a general tool for promoting important cognitive skills’.
Dahlin, E., Stigsdotter Neely, A., Larsson, A., Bäckman, L. & Nyberg, L. (2008). Transfer of Learning After Updating Training mediated by the Striatum, Science, 320(5882), 1510-1512.
The ultimate goal for most researchers who work in the field of working memory training is to show that training leads to gains in other tasks that differ from the training tasks (e.g. to maths or reading). This study showed that transfer to other tasks following working memory training is likely only if the non-trained task engages overlapping regions of the brain as those activated during training.
Dunning, D.L., Holmes, J., & Gathercole, S. (2013) Does working memory training lead to generalised improvements in children with low working memory? A randomised controlled trial, Developmental Science, 16(6), 915-926
Randomised controlled trials (RCT) are the gold standard for intervention research. This type of design means random allocation to intervention group and blind-assessments before and after training. This is shameless promotion of my own work. That said it is the largest single RCT to date. Here children aged 7–9 years with poor working memory received adaptive Cogmed working memory training, non-adaptive Cogmed working memory training, or no training. Outcome measures included a broad range of tasks of learning and cognition. Adaptive training was associated with improvements in tests of working memory, but there was no evidence of transfer to other cognitive assessments or standardised tests of learning. The gains made in working memory were partly sustained one year after training.
Harrison, T. L., Shipstead, Z., Hicks, K. L., Hambrick, D. Z., Redick, T. S., & Engle, R. W. (2013). Working Memory Training May Increase Working Memory Capacity but Not Fluid Intelligence. Psychological Science. doi: 10.1177/0956797613492984.
This was an RCT study with adults who trained on a series of complex span working memory tasks. The complex span task is the type used most frequently in working memory training studies and has both processing and storage demands. The authors found that training led to an improvement in other non-trained working memory tasks. However, they found that this benefit did not extend to improvements in measures of fluid intelligence - our ability to think logically and solve problems in novel situations without using our acquired knowledge. Gains in fluid intelligence have been reported in several training studies that train on complex span tasks and on n-back training tasks (see studies 5 & 6).
Jaeggi, S.M., Buschkuehl, M., Jonides, J., & Perrig, W.J. (2008). Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences of the United States of America, 105, 6829–6833.
N-back is a working memory task that involves the presentation of a series of stimuli such as letters, with the participant responding when the current stimuli matches the one n-steps earlier in the sequence (typically either 2- or 3-steps back). Jaeggi and colleagues developed a dual n-back training paradigm in which participants had to judge whether either of two targets on screen (a digit and a spatial location) matched the stimuli presented n-steps earlier. Training led to gains in fluid intelligence and more importantly perhaps, also showed that gains were dose dependent with more training equaling bigger improvements in fluid intelligence.
Klingberg, T., Fernell, E., Olesen, P.J., Johnson, M., Gustafsson, P., Dahlstrom, K. et al. (2005). Computerised training of working memory in children with ADHD-a randomised, controlled trial. Journal of the American Academy of Child and Adolescent Psychiatry, 44, 177-186.
This is comfortably the most cited paper in the field of working memory training and was the first to use an RCT design. Children with ADHD often have associated working memory problems. Klingberg and colleagues showed that Cogmed working memory training was effective for a group of children with ADHD aged between 7 and 12 years. Compared to a control group who completed a placebo version of the training, the trained group made improvements in short-term memory, response inhibition and complex reasoning (fluid intelligence) and there were also reductions in parent ratings of inattention and hyperactivity/impulsivity. Crucially this was the first paper to show the effects of training could be sustained, in this case for 3 months.
Melby-Lervåg, M., & Hulme, C. (2012). Is Working Memory Training Effective? A Meta-Analytic Review. Developmental Psychology, 49(2),270-91.
Meta-analyses are systematic reviews that contrast and combine results from different studies. Melby-Lervåg and Hulme examined 23 studies of different types of working memory training that included control groups. Studies were included regardless of the age of sample and whether the sample was typical or atypical. The authors drew two major conclusions. The first was that training, for the most part, leads to reliable short-term improvements in working memory skills and the second was that these training effects do not usually generalize to improvements in areas such as inhibition, word decoding or arithmetic.
Olesen, P.J., Westerberg, H., & Klingberg, T. (2004). Increased prefrontal and parietal activity after training of working memory. Nature Neuroscience 7, 75 – 79.
In this study, changes in brain activity following working memory training were examined. Brain activity was measured with functional magnetic resonance imaging before, during and after training. After training, brain activity that is related to working memory increased in the middle frontal gyrus and superior and inferior parietal cortices. The authors concluded that the changes in cortical activity could be evidence of training-induced plasticity in the neural systems that underlie working memory.
Redick, Thomas S., et al. No evidence of intelligence improvement after working memory training: A randomized, placebo-controlled study. Journal of Experimental Psychology: General 142.2 (2013): 359.
Participants trained on either a dual n-back program (similar to study 6) or an adaptive visual search program or were allocated to a no-contact control group. Multiple measures of fluid intelligence, multitasking, working memory capacity, crystallized intelligence, and perceptual speed were administered before and after training. Participants improved on both training tasks but not on any of the cognitive ability tests. This finding contradicts Jaeggi and colleagues assertion that n-back working memory training leads to gains in fluid intelligence.
Turley-Ames, K.J. , & Whitfield, M.M. (2003). Strategy training and working memory task performance. Journal of Memory and Language, 49, 446-468.
An oldie, in working memory training terms, but a goodie. In this study the experimenters examined how instructing participants to use particular memory strategies influenced working memory performance. The design was simple; measures of working memory and reading were given to all participants and then half were taught a rehearsal strategy. The group who were taught the strategy improved more than the group who were not. Those with low working memory benefitted the most from the rehearsal strategy.
Want to know more? Here are some recommended reviews of working memory training:
Klingberg T (2010). Training and plasticity of working memory. Trends in Cognitive Science, 14(7): 317-324.
Shipstead, Z., Redick, T.S., & Engle, R. W. (2012). Is working memory training effective? Psychological Bulletin, 138(4), 628.
About the author:
Dr Darren Dunning is a researcher at the University of East Anglia and a trainer on the Cogmed Coach Training courses.
Date posted: December 10, 2013