The Science Behind Memory Improvement

This page lists memory research evidence that backs up much of the advice and techniques I explain on this website. Why the need for a page like this?

There has always been too much hype associated with memory improvement. It's easy to find "snake oil salesmen" selling magic pills they say give anyone a perfect memory.

But you want good reasons for what you do, and so do I. Thus the importance of scientific research.

The rest of this site explains memory improvement habits and techniques. Make them your own, and you will get results!

This page lists memory research studies that support the advice on this site. These studies help explain why my advice is effective. You might also want to check out my quick guide on how memory works.

Click the blue and white arrows below to jump down to the related section:

Don't expect this research to address every question or technique, however. Science has not yet solved the puzzle of human memory (though great strides have been made). Some advice is presented on this site because I know it works, from having tried it myself.

Below are research studies I think are especially relevant. I'll continue to add to this page as I learn more, and as additional studies are released.

Brain Games & Memory - Research Studies Jump to top

The brain needs stimulation to function at its best, and playing brain games is one way to keep your mind active. Scientific online brain games, in particular, have been shown to increase memory, concentration, and other brain skills.

• (1) Mentally stimulating activities protect against Alzheimer's Disease. Ten individuals with Alzheimer's Disease were studied together with 65 healthy people and 11 young controls. This study found that those who participated throughout their lives in mentallly stimulating activity had less beta-amyloid (a suspected cause of Alzheimer's Disease) deposited in their cortex. The authors conclude that individuals who participated in greater early and mid-life cognitive activity (including playing brain games, reading, and writing) had lower amyloid uptake, perhaps reducing the onset and progression of Alzheimer's.

  Reference: Susan M. Landau, PhD, Shawn M. Marks, BS, et al. "Association of Lifetime Cognitive Engagement and Low ß-Amyloid Deposition" Archives of Neurology, Published online January 23, 2012. http://dx.doi.org/10.1001/archneurol.2011.2748

• (2) Brain training improves memory in child cancer patients. Twenty-three pediatric cancer survivors aged 7 to 19 completed 40 sessions of Lumosity computerized brain training. Participants increased mental flexibility, processing speed, declarative memory, and prefrontal cortex activation. (The prefrontal cortex is where executive functions such as planning, organizing, focusing attention, and remembering complex concepts and events occurs.) The study's authors concluded that these computerized cognitive exercises "can be successfully implemented at home and...may be effective for improving executive and memory skills in this group."

  Reference: Shelli R. Kesler, Norman J. Lacayo, et al. "A pilot study of an online cognitive rehabilitation program for executive function skills in children with cancer-related brain injury." Brain Injury, Vol. 25, No. 1 , Pages 101-112. Informa Healthcare, January 2011. http://dx.doi.org/10.3109/02699052.2010.536194

• (3) Brain training improves working memory in adult brain injury patients. Twenty-one individuals, averaging 43 years old, with an average of 37 months since a traumatic brain injury trained daily for five weeks using a computerized working memory program. Follow-up occurred 4 weeks and 20 weeks after training. Participants who trained experienced significant improvement in working memory tests and tasks at both 4 and 20 weeks compared to controls who did not train. The study's authors concluded that, "...structured and intense computerized working memory training improves subjects' cognitive functioning."

  Reference: Anna Lundqvist, Kerstin Grundstrom, et al. "Computerized training of working memory in a group of patients suffering from acquired brain injury." Brain Injury, Vol. 24, No. 10 , Pages 1173-1183. Informa Healthcare, September 2010. http://dx.doi.org/10.3109/02699052.2010.498007

• (4) Cognitive training decreases risk of cognitive decline. This 800-page research study, funded by the National Institutes of Health (NIH), reviewed extensive past research to determine which activities have the most impact on brain health. Of all factors, including diet, supplements, and exercise, only "cognitive training" (i.e., brain games training) was found to be closely associated with a decreased risk of mental decline.

  Reference: Williams JW, Plassman BL, et al. "Preventing Alzheimer's Disease and Cognitive Decline. Evidence Report/Technology Assessment No. 193. (Prepared by the Duke Evidence-based Practice Center under Contract No. HHSA 290-2007-10066-I.)" Agency for Healthcare Research & Quality (AHRQ), U.S. Dept. of Health & Human Services. Publication No. 10-E005. Rockville, MD: Agency for Healthcare Research and Quality. April 2010. http://www.ahrq.gov/downloads/pub/evidence/pdf/alzheimers/alzcog.pdf

• (5) Computer software improves attention and memory. The Brain Fitness Program, a computerized brain training program created by Posit Science, was shown to significantly improve memory, attention, and information processing. Those who trained with the software were twice as fast in processing information, and they scored as well on memory and attention tests as those 10 years younger. Researchers concluded that "...the experimental program improved generalized measures of memory and attention more than an active control program."

  Reference: Smith GE, Housen P, et al. "A cognitive training program based on principles of brain plasticity: results from the Improvement in Memory with Plasticity-based Adaptive Cognitive Training (IMPACT) study." Journal of the American Geriatric Society, 57(4):594-603. April 2009. http://www.ncbi.nlm.nih.gov/pubmed/19220558

• (6) Dual n-back computerized training increases fluid intelligence. Seventy healthy adults practiced a difficult memory exercise called "dual n-back training" on the computer for 8, 12, 17, or 19 days, five days a week. Those who trained increased their working memory and fluid intelligence significantly compared to controls who did not train. The more days trained, the larger the increase. Fluid intelligence is a component of creative problem solving and a major contributor to a person's intelligence quotient (IQ).

  Reference: Jaeggi, S., Buschkuehl, M., et al. "Improving fluid intelligence with training on working memory." Proceedings of the National Academy of Sciences (PNAS), 105(19): 6829-6833. April 28, 2008. DOI: http://dx.doi.org/10.1073/pnas.0801268105

Diet & Memory - Research Studies Jump to top

What you eat and drink every day (and in what quantity), as well as which vitamins and supplements you take, has a significant impact on your brain and memory. The studies below highlight the fact that what you eat can significantly affect your memory. To protect your memory, eat more brain foods.

• (1) Overeating may double your risk of memory loss. The more calories you eat per day, the higher your risk of developing mild cognitive impairment when you reach age 70 and above. Mild cognitive impairment (MCI) is the stage between normal age-related memory loss and full-blown Alzheimer's disease. Researchers studied 1,200 individuals ages 70-79, including those with and without MCI. They were divided into three groups based on number of calories consumed per day. The conclusion: the group in the top third (those eating the most calories) had twice the risk of contracting mild congnitive impairment. Cutting calories and eating healthy does more than preserve your physical health - it protects your brain from significant memory loss. Looked at another way, habitual overeating appears to directly cause memory loss and cognitive impairment.

  Reference: Yonas Geda, MD, MSc, Marion Ragossnig, Lewis K. Roberts, et. al. American Academy of Neurology (AAN), February 13, 2012. http://www.aan.com/globals/axon/assets/9279.pdf

• (2) How does a diet high in DHA improve memory? Research has demonstrated that eating fish or taking fish oil supplements can improve memory. But what takes place in the brain to make this happen? It turns out that DHA, an omega fatty acid found in fish, becomes concentrated in the hippocampus, a memory center of the brain. Researchers at the University of Alberta discovered that DHA improves communication between the cells in the hippocampus. The more DHA that accumulates there, the better the memory neurons are able to relay messages. Importantly, this study also confirmed that when DHA is added to the diet (through eating more fish or through omega supplementation), the extra DHA obtained from the diet does in fact get stored in the brain.

  Reference: Steve Connor, Gustavo Tenorio, et al. DHA supplementation enhances high-frequency, stimulation-induced synaptic transmission in mouse hippocampus. Applied Physiology, Nutrition, and Metabolism. 20 June 2012. DOI: http://dx.doi.org/10.1139/h2012-062

Aerobic Exercise & Memory - Research Studies Jump to top

The hippocampus, a curved structure in the brain, is vital to memory formation. Many studies indicate that a bigger hippocampus means a better memory. Research also shows that you can increase the size of your hippocampus through aerobic exercise, regardless of your age.

• (1) Exercise increases hippocampus size and improves memory. One year of brisk walking by older adults caused their hippocampus to grow by 2 percent. They walked 40 minutes, three days a week. The control group that did not walk saw their hippocampus shrink by over 1 percent, due to normal aging.

  Reference: Kirk I. Erickson, Michelle W. Voss, et al. "Exercise training increases size of hippocampus and improves memory." Proceedings of the National Academy of Science (PNAS), Jan. 31, 2011. DOI: http://dx.doi.org/10.1073/pnas.1015950108

• (2) Physically fit children perform better on memory tests. Children age 9 and 10 who were more physically fit had a 12 percent bigger hippocampus and scored higher on a test of relational memory (the memory-associated ability to relate and integrate information). Fitness was measured by how efficiently the student's body used oxygen while running on a treadmill ("the gold standard measure of fitness"). The size of their hippocampus was measured by MRI scan.

  Reference: Laura Chaddock, Kirk I. Erickson, et al. "A neuroimaging investigation of the association between aerobic fitness, hippocampal volume and memory performance in preadolescent children." Brain Research, 1358: 172-183. October 28, 2010. DOI: http://dx.doi.org/10.1016/j.brainres.2010.08.049

• (3) Aerobic fitness is correlated with hippocampal size. Physical fitness is directly associated with a larger hippocampus and better spatial memory in older adults. Participants in this study who were more fit were shown to have a significantly larger hippocampus. According to the study authors, "If you stay fit, you retain key regions of your brain involved in learning and memory."

  Reference: Kirk I. Erickson, Ruchika S. Prakash, et al. "Aerobic fitness is associated with hippocampal volume in elderly humans." Hippocampus, 19: 1030-1039. October 2009. DOI: http://dx.doi.org/10.1002/hipo.20547

Meditation & Memory - Research Studies Jump to top

Meditation is an ancient mental discipline little practiced in Western countries until recently. While at first glance it appears those Tibetan monks aren't doing anything, they are engaged in a brain plasticity exercise that literally reshapes their brain in ways that improve memory and attention span.

• (1) Meditation changes brain structure, improving attention span. Gray matter in the hippocampal memory center of the brain became denser in participants who meditated 30 minutes a day for 8 weeks. Hippocampal density was measured by MRI scan. The control group who did not meditate experienced no changes in brain density. "The results suggest that participation in MBSR [mindfulness meditation] is associated with changes in gray matter concentration in brain regions involved in learning and memory processes..."

  Reference: Britta K. Holzel, James Carmody, et al. "Mindfulness practice leads to increases in regional brain gray matter density." Psychiatry Research: Neuroimaging, 2011; 191 (1): 36. DOI: http://dx.doi.org/10.1016/j.pscychresns.2010.08.006

• (2) Short 20-minute meditation sessions improve concentration. Before you can place anything in memory, you must focus on it. Not only does regular meditation improve concentration, but the benefits are achievable in as little as 20 minutes per day according to this study. Participants did much better than the control group on timed concentration and memory tests such as computer adaptive n-back tasks.

  Reference: Fadel Zeidan, Susan K. Johnson, et al. "Mindfulness meditation improves cognition: Evidence of brief mental training." Consciousness and Cognition, 19(2): 597-605, June 2010. DOI: http://dx.doi.org/10.1016/j.concog.2010.03.014

Memory Systems & Memory - Research Studies Jump to top

Memory Systems based on visualization & association are some of the most powerful techniques you can use to memorize any type of material. In fact, if there is one set of habits that you take away from this website, I hope that it's to regularly use memory systems such as the Link method, Journey method, and Peg method.

• (1) Story Memory Technique improves memory in multiple sclerosis patients. Damage to the brain caused by multiple sclerosis can lead to short-term memory loss. A study by the Kessler Foundation shows that training MS patients in the Story Memory Technique (similar to the Link Memory Technique) can improve their memory. Functional MRI (fMRI) was used to show that brain activity of patients who trained with the Story Technique was significantly higher than in those who had not trained. This research helps support the idea that memory training and other cognitive rehabilitation techniques can be effective for sufferers of MS and potentially for others with brain disease.

  Reference: Nancy D. Chiaravalloti, Glenn Wylie, et al. "Increased cerebral activation after behaviorial treatment for memory deficits in MS." Journal of Neurology, 15 January 2012: 1-10. DOI: http://dx.doi.org/10.1007/s00415-011-6353-x

• (2) Visualization & association keywords create strong memory links. This study showed that taking practice tests helps improve memory. The conclusion was that during a practice test, the student develops effective "mediators" (mental hints) that they normally wouldn't think of during regular studying. The true insight, in my opinion, is that students should be actively creating these mediators during their regular study sessions! As the study's author points out, for foreign language tests, "A more effective strategy is to develop a keyword that connects the foreign language word with the English word. 'Wingu' sounds like 'wing,' birds have wings and fly in the 'clouds.'" What she is describing, of course, is visualization & association, a memory technique explained on this website.

  Reference: Mary A. Pyc, Katherine A. Rawson. "Why Testing Improves Memory: Mediator Effectiveness Hypothesis." Science, 15 October 2010: 335. DOI: http://dx.doi.org/10.1126/science.1191465

• (3) Forgotten information is still in your brain. Eleven female and five male patients were put in an fMRI machine that measures blood flow in the brain. Even when the students could not recall any of the information they had been shown earlier, a repeated brain scan showed the same pattern as when they were exposed to the information originally. Though the students couldn't remember the details, the information was apparently still in their brain. The implication for memory improvement is that we must create better "hooks" for retrieving details from memory. These hooks are the visualization & association "memory systems" described on this website.

  Reference: Jeffrey D. Johnson, Susan G.R. McDuff, et al. "Recollection, Familiarity, and Cortical Reinstatement: A Multivoxel Pattern Analysis." Neuron, Vol. 63 Issue 5, September 8, 2009. DOI: http://dx.doi.org/10.1016/j.neuron.2009.08.011

Mood & Memory - Research Studies Jump to top

Many studies have shown that restful sleep consolidates and strengthens memories. Sleep makes memories more accessible and usable. To improve your memory, improve the quality of your sleep (and the quantity, if you are not sleeping enough).

• (1) Learning strengthened by latter-stage sleep. Spindle-rich sleep that occurs in the latter half of a night's sleep is responsible for strengthened learning ability. During this stage of sleep, memories are transferred from short-term storage in the brain's hippocampus to long-term storage in the prefrontal cortex. The study's author concludes that, "..if you sleep six hours or less, you are shortchanging yourself. You will have fewer spindles, and you might not be able to learn as much." Sleep seeks out memory functions and restores their critical functions.

  Reference: Bryce A. Mander, Sangeetha Santhanam, et al. "Wake deterioration and sleep restoration of human learning." Current Biology, 2011; 21 (5): R183. March 8, 2011. DOI: http://dx.doi.org/10.1016/j.cub.2011.01.019

• (2) Sleep reorganizes memories and improves creativity. As this study showed, sleep reorganizes and restructures memories, picking out the most important details. According to the study's author, "We can get away with less sleep, but it has a profound effect on our cognitive abilities."

  Reference: Elizabeth A. Kensinger and Jessica D. Payne. "Sleep's Role in the Consolidation of Emotional Episodic Memories." Current Directions in Psychological Science, Vol. 19, No. 5: 290-295. October 12, 2010. DOI: http://dx.doi.org/10.1177/0963721410383978

• (3) Sleep strengthens memories, protects from interference. Non-distracted participants who slept after learning 20 word pairs recalled 12 percent more than other non-distracted participants who did not sleep before testing. Distracted participants who slept remembered 44 percent more than distracted participants who did not sleep. The study's author concluded that sleep not only protects memories from interference (competing information), it makes memories stronger.

  Reference: Jeffrey Ellenbogen. "Sleep Strengthens Your Memory." American Academy of Neurology, 59th Annual Meeting in Boston. April 25, 2007. http://www.aan.com/press/index.cfm?fuseaction=release.view&release=460

Sleep & Memory - Research Studies Jump to top

Many studies have shown that restful sleep consolidates and strengthens memories. Sleep makes memories more accessible and usable. To improve your memory, improve the quality of your sleep (and the quantity, if you are not sleeping enough).

• (1) Learning strengthened by latter-stage sleep. Spindle-rich sleep that occurs in the latter half of a night's sleep is responsible for strengthened learning ability. During this stage of sleep, memories are transferred from short-term storage in the brain's hippocampus to long-term storage in the prefrontal cortex. The study's author concludes that, "..if you sleep six hours or less, you are shortchanging yourself. You will have fewer spindles, and you might not be able to learn as much." Sleep seeks out memory functions and restores their critical functions.

  Reference: Bryce A. Mander, Sangeetha Santhanam, et al. "Wake deterioration and sleep restoration of human learning." Current Biology, 2011; 21 (5): R183. March 8, 2011. DOI: http://dx.doi.org/10.1016/j.cub.2011.01.019

• (2) Sleep reorganizes memories and improves creativity. As this study showed, sleep reorganizes and restructures memories, picking out the most important details. According to the study's author, "We can get away with less sleep, but it has a profound effect on our cognitive abilities."

  Reference: Elizabeth A. Kensinger and Jessica D. Payne. "Sleep's Role in the Consolidation of Emotional Episodic Memories." Current Directions in Psychological Science, Vol. 19, No. 5: 290-295. October 12, 2010. DOI: http://dx.doi.org/10.1177/0963721410383978

• (3) Sleep strengthens memories, protects from interference. Non-distracted participants who slept after learning 20 word pairs recalled 12 percent more than other non-distracted participants who did not sleep before testing. Distracted participants who slept remembered 44 percent more than distracted participants who did not sleep. The study's author concluded that sleep not only protects memories from interference (competing information), it makes memories stronger.

  Reference: Jeffrey Ellenbogen. "Sleep Strengthens Your Memory." American Academy of Neurology, 59th Annual Meeting in Boston. April 25, 2007. http://www.aan.com/press/index.cfm?fuseaction=release.view&release=460

Study Skills & Memory - Research Studies Jump to top

Which study methods you use makes a big difference on how much of the material you can later recall. Some of the best study skills include 1) reducing interference, 2) spacing it out, 3) using whole and part learning, 4) reciting the material, and 5) using a study system such as SQR3. Here is some research related to study skills.

• (1) Practice "retrieval" (i.e., recite) to remember more. To recall more, read less and retrieve more. This research showed that frequent self-testing while you study increases your ability to recall what was learned. Participants who studied using retrieval self-testing remembered 50 percent more science material than others who studied the same information by drawing concept maps.

  Reference: J. D. Karpicke, J. R. Blunt. "More Learning than Elaborative Studying with Concept Mapping." Science, Vol. 331, No. 6018, pp. 772-775, 11 February 2011. DOI: http://dx.doi.org/10.1126/science.1199327

• (2) Spaced out study sessions result in better learning. This study proved what you already know: short-term cramming doesn't work. Over 1,000 participants engaged in two separate study sessions followed by an exam. During the first study session they were taught a series of obscure but true facts. The second session was a review of the same information. The researchers found that the longer the time between the two study sessions, the better the students performed on the exam. The study's author advises, "If you want to remember information for just a week, it is probably best if study sessions are spaced out over a day or two. On the other hand, if you want to remember information for a year, it is best for learning to be spaced out over about a month. It seems plausible that whenever the goal is for someone to remember information over a lifetime, it is probably best for them to be re-exposed to it over a number of years."

  Reference: J. D. Karpicke, J. R. Blunt. "Spacing Effects in Learning: A Temporal Ridgeline of Optimal Retention." Psychological Science, 19, 1095-1102. November 1, 2008. DOI: http://dx.doi.org/10.1111/j.1467-9280.2008.02209.x

• (3) Overlearn to reduce memory interference. This study showed that the more deeply you understand the material, the more protected your memory is from interference from similar information. Therefore, to strengthen your memory overlearn the information (continue studying even after you think you know it well).

  Reference: Isabel L. Beck, Patricia A. Carpenter. "Cognitive Approaches to Understanding Reading: Implications for Instructional Practice." American Psychologist, Vol 41(10), October 1986, 1098-1105. DOI: http://dx.doi.org/10.1037/0003-066X.41.10.1098

How Does the Author of This Site Use This Information?

You may wonder how I've incorporated this knowledge in my own life. It is one thing to know about something, quite another to benefit from it. The secret is to establish habits based on what is known to give good results.

For example, I know that studies indicate brisk walking and other types of aerobic exercise stimulate growth of the hippocampus, an area of the brain vital to memory.

So I take my dog on long, brisk walks three or four days a week. It's good for my memory (and my physical health), and it's good for my dog.

As another example, research shows that brain games can improve individual brain skills such as concentration, logical reasoning, and reaction time. So I play free online brain games as often as I can. It's fun, too!

There is a good reason why "habit formation" is critical. Unlike problems in life that can be solved by a single action (changing a flat tire, for example), improving your brain requires consistent, repeated actions. The benefits of these actions are cumulative.

One brisk walk a month or playing brain games once a week or meditating once in awhile won't accomplish anything. You must perform these activities repeatedly, and often.

Yes, memory improvement takes time and effort, but it is well worth it. Your brain is your main tool for success in life. The more powerful your brain, and the better it functions, the more satisfied, happier, and effective you'll be!

Published: 03/27/2011
Last Updated: 05/03/2021