Simply Smarter Research Library

80+ studies. One conclusion: the brain responds to training.

Simply Smarter is built on NACD’s 45 years of direct clinical practice — and that practice is informed by decades of research. Below are the peer-reviewed studies organized by topic. This isn’t a marketing claim. It’s the scientific foundation.

References List

Working memory is the brain’s mental workspace — the capacity to hold and manipulate information in real time. Research consistently shows it is one of the strongest predictors of academic success, reasoning ability, and general intelligence. Unlike IQ, it responds directly to training.

  • Baddeley, A. D., & Hitch, G. (1974). Working memory. In G. A. Bower (Ed.), The psychology of learning and motivation: Advances in research and theory (Vol. 8, pp. 47–89). New York: Academic Press.
  • Baddeley, A. D. (1996). Exploring the central executive. Quarterly Journal of Experimental Psychology, 49A, 5–28.
  • Baddeley, A. D. (2000). The episodic buffer: a new component of working memory? Trends in Cognitive Sciences, 4, 417–423.
  • Conway, A., Kane, M. J., & Engle, R. W. (2003). Working memory capacity and its relation to general intelligence. Trends in Cognitive Sciences, 7(12), 547–552.
  • Cowan, N. (1998). Attention and memory: An integrated framework. New York: Oxford University Press.
  • Cowan, N. (2008). What are the differences between long-term, short-term, and working memory? Progress in Brain Research, 169, 323–338.
  • Cowan, N. (2013). Working memory underpins cognitive development, learning, and education. Educational Psychology Review, 26(2), 197–223.
  • Dang, C., et al. (2013). Why is working memory related to intelligence? Different contributions from storage and processing. Memory, 22(4), 426–441.
  • Engle, R. W. (2002). Working memory capacity as executive attention. Current Directions in Psychological Science, 11, 19–23.
  • Cornoldi, C., & Mammarella, I. (2013). The structure of working memory and how it relates to intelligence in children. Intelligence.
  • Flores-Mendoza, C. (2003). Working memory and intelligence. Personality and Individual Differences.
  • Presti, G. L. (2014). The crucial role of working memory in intellectual functioning. European Psychologist.
  • Rydzewska, K. (2016). Three functional aspects of working memory as strong predictors of early school achievements. Polish Psychological Bulletin.
  • Spanoudis, G. (2016). Cognitive correlates of developing intelligence: The contribution of working memory, processing speed and attention. Intelligence.
  • Süss, H.-M., et al. (2002). Working-memory capacity explains reasoning ability — and a little bit more. Intelligence, 30, 261–288.
  • Wittmann, W. (2002). Working-memory capacity explains reasoning ability — and a little bit more. Intelligence.
  • Wittmann, W. (2008). Which working memory functions predict intelligence? Intelligence.

Multiple controlled studies show that adaptive working memory training produces measurable improvements in academic performance — including reading comprehension, math, and the ability to follow multi-step instructions. Gains transfer beyond the training tasks themselves.

  • Ariës, R. J., Groot, W., & Maassen van den Brink, H. (2015). Improving reasoning skills in secondary history education by working memory training. British Educational Research Journal, 41(2), 210–228.
  • Ariës, R. J., et al. (2015). Is working memory training effective in enhancing school based reasoning achievements? A systematic review. Working Paper No. 15-02.
  • Au, J., et al. (2014). Improving fluid intelligence with training on working memory: A meta-analysis. Psychonomic Bulletin and Review.
  • Beatty, E. L., & Vartanian, O. (2015). The prospects of working memory training for improving deductive reasoning. Frontiers in Human Neuroscience, 9, 56.
  • Buschkuehl, M., et al. (2008). Impact of working memory training on memory performance. Psychology and Aging, 23(4), 743–753.
  • Cherqaoui, L., & El Haddadi, A. (2024). The impact of working memory training on reading performance and neurological impairments in individuals with dyslexia. Science Step Journal, II(6), 28–39.
  • Dahlin, K. (2010). Effects of working memory training on reading in children with special needs. Reading and Writing, 24, 479–492.
  • Jaeggi, S. M., et al. (2008). Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences, 105(19), 6829–6833.
  • Karbach, J., et al. (2014). Adaptive working-memory training benefits reading, but not mathematics in middle childhood. Child Neuropsychology.
  • Nevo, E., & Breznitz, Z. (2014). Effects of working memory and reading acceleration training on improving working memory abilities and reading skills among third graders. Child Neuropsychology, 20(6), 752–765.
  • Von Bastian, C. C., & Oberauer, K. (2013). Effects and mechanisms of working memory training: A review. Psychological Research, 78.
  • Von Bastian, C. C., & Oberauer, K. (2013). Distinct transfer effects of training different facets of working memory capacity. Journal of Memory and Language, 69(1), 36–58.

Children with low working memory are consistently identified by teachers as inattentive and underperforming — regardless of their intelligence. This research demonstrates why processing-based intervention, not more instruction, is the appropriate response for struggling learners.

  • Alloway, T. (2005). Working memory in children with reading disabilities. Journal of Experimental Child Psychology.
  • Alloway, T. P., Gathercole, S. E., & Pickering, S. J. (2006). Verbal and visuo-spatial short-term and working memory in children: Are they separable? Child Development, 77, 1698–1716.
  • Alloway, T., & Gathercole, S. E. (2008). Evaluating the validity of the Automated Working Memory Assessment. Educational Psychology, 28(7), 725–734.
  • Alloway, T., & Gathercole, S. E. (2009). The cognitive and behavioral characteristics of children with low working memory. Child Development, 80(2), 606–621.
  • Gathercole, S. E., & Alloway, T. P. (2004). Working memory and classroom learning. Dyslexia Review, 15, 4–9.
  • Gathercole, S. E., Pickering, S. J., Ambridge, B., & Wearing, H. (2004). The structure of working memory from 4 to 15 years of age. Developmental Psychology, 40, 177–190.
  • Gropper, R. (2013). Working memory training in college students with attention deficit. Ontario Institute for Studies in Education.
  • Holmes, J., Gathercole, S. E., & Dunning, D. L. (2009). Adaptive training leads to sustained enhancement of poor working memory in children. Developmental Science.
  • Holmes, J., & Gathercole, S. E. (2014). Taking working memory training from the laboratory into schools. Educational Psychology, 34(4), 440–450.
  • Lee, K., Ng, E., & Ng, S. (2009). The contributions of working memory and executive functioning to problem representation and solution generation in algebraic word problems. Journal of Educational Psychology, 101(2), 373–387.
  • Van der Sluis, S., et al. (2007). Executive functioning in children, and its relations with reasoning, reading and arithmetic. Intelligence, 35, 427–449.

How quickly the brain receives and processes information — auditory and visual — has direct impact on reading, attention, and the ability to track fast-moving conversation or instruction. Training processing speed produces broad improvements in cognitive efficiency across ages.

  • Cowan, N. (1998). Visual and auditory working memory capacity. Trends in Cognitive Sciences, 2(3), 77.
  • Dalton, P., Santangelo, V., & Spence, C. (2009). The role of working memory in auditory selective attention. Quarterly Journal of Experimental Psychology, 62(11), 2126–2132.
  • Hale, S. (2000). Relationships among processing speed, working memory, and fluid intelligence in children. Biological Psychology.
  • Klingberg, T. (2009). The overflowing brain: Information overload and the limits of working memory. New York: Oxford University Press.
  • Kraus, N., Strait, D. L., & Parbery-Clark, A. (2012). Cognitive factors shape brain networks for auditory skills: Spotlight on auditory working memory. Annals of the New York Academy of Sciences, 1252(1), 100–107.
  • Kumar, S., et al. (2016). A brain system for auditory working memory. Journal of Neuroscience, 36(16), 4492–4505.
  • Kunnath, S. (2016). Auditory short term memory and academic achievement in normal school going children. International Journal of Health Sciences and Research.
  • Magimairaj, B. M., & Nagaraj, N. K. (2018). Working memory and auditory processing in school-age children. Language, Speech, and Hearing Services in Schools, 49(3), 409–423.
  • Martinkauppi, S., et al. (2000). Working memory of auditory localization. Cerebral Cortex, 10(9), 889–898.
  • Plessis, S. D., & Maree, D. (2019). Auditory short-term memory, visual sequential memory and inductive reasoning matter for academic achievement. EDULEARN19 Proceedings. https://doi.org/10.21125/EDULEARN.2019.0711
  • Spanoudis, G. (2016). Cognitive correlates of developing intelligence: The contribution of working memory, processing speed and attention. Intelligence.
  • Baddeley, A., & Logie, R. (2014). Auditory imagery and working memory. In Auditory imagery (pp. 179–197). Psychology Press.

Neuroplasticity is now universally accepted in neuroscience. Brain imaging studies confirm measurable physical changes in brain structure after cognitive training — in children, adults, and older adults alike. NACD was operating on this principle decades before it had a name in scientific literature.

  • Davidson, M. C., et al. (2006). Development of cognitive control and executive functions from 4 to 13 years.
  • Gazzaniga, M. S., et al. (2009). Cognitive neuroscience: The biology of the mind (3rd ed.). New York: W.W. Norton.
  • Olesen, P., Westerberg, H., & Klingberg, T. (2004). Increased prefrontal and parietal activity after training of working memory. Nature Neuroscience, 7(1).
  • Paus, T. (2005). Mapping brain maturation and cognitive development during adolescence. Trends in Cognitive Sciences, 9(2), 60–68.
  • Salminen, T., et al. (2016). Increased integrity of white matter pathways after dual n-back training. Neuroimage, 133, 244–250.
  • Sander, M. C., et al. (2012). Lifespan age differences in working memory: A two-component framework. Neuroscience and Biobehavioral Reviews, 36, 2007–2033.
  • Westerberg, H., & Klingberg, T. (2007). Changes in cortical activity after training of working memory — a single-subject analysis. Physiology and Behavior, 92(1–2), 186–192.
  • Willis, S. L., et al. (2006). Long-term effects of cognitive training on everyday functional outcomes in older adults. JAMA, 296(23), 2805–2814.

Children with ADHD show measurable deficits in working memory and processing capacity. Adaptive training has shown sustained improvements in attention, executive function, and behavior in children with attention challenges — without pharmacological intervention.

  • Davidson, M. C., et al. (2006). Development of cognitive control and executive functions from 4 to 13 years.
  • Engle, R. W. (2002). Working memory capacity as executive attention. Current Directions in Psychological Science, 11, 19–23.
  • Fuster, J. M. (2003). Cortex and mind: Unifying cognition. New York: Oxford University Press.
  • Gropper, R. (2013). Working memory training in college students with attention deficit. Ontario Institute for Studies in Education.
  • Lustig, C., Hasher, L., & Tonev, S. T. (2001). Inhibitory control over the present and the past. European Journal of Cognitive Psychology, 13(1–2), 107–122.
  • Westerberg, H., et al. (2004). Visuo-spatial working memory: A sensitive measurement of cognitive deficits in ADHD. Child Neuropsychology, 10, 155–161.
  • Westerberg, H., & Klingberg, T. (2007). Changes in cortical activity after training of working memory. Physiology and Behavior, 92(1–2), 186–192.

This list is not exhaustive. NACD’s clinical approach is informed by this research and by over 1 million hours of direct application with individuals across every ability level — from children with Down syndrome to gifted students to seniors. Questions or citation requests: simplysmarter@nacd.org

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