In an effort to understand why and how listeners remember some spoken utterances more clearly than others, University of Texas at Austin researchers Sandie Keerstock and Rajka Smiljanic are specifically looking at ways in which clarity of speaking style can affect memory. In one experiment, 30 native and 30 nonnative English listeners were presented with 72 sentences, broken down into six blocks of 12 sentences each. These sentences - such as "The grandfather drank the dark coffee" or "The boy carried the heavy chair" - were alternately produced in two different styles: "clear" speech, in which the speaker talked slowly, articulating with great precision, and a more casual and speedily delivered "conversational" manner.
After hearing each block of a dozen sentences, listeners were asked to recall verbatim the sentences they had heard by writing them down on a sheet of paper, after being given a clue such as "grandfather" or "boy." Both groups of listeners - native and nonnative - did better when sentences were presented in the clear speaking style. This is in line with their previous study in which clearly spoken sentences were recognized better than casual sentences as previously heard by both groups of listeners. The UT Austin researchers offer a possible explanation for these results: When a speaker is talking faster or failing to enunciate as crisply, listeners have to work harder to decipher what's being said. More mental resources, consequently, are drawn toward that task, leaving fewer resources available for memory consolidation.
Clearly produced speech could benefit students in the classroom and patients receiving instructions from their doctors, Smiljanic says. "That appears to be an efficient way of conveying information, not only because we can hear the words better but also because we can retain them better." In their next round of experiments, she and Keerstock will focus on the speakers rather than the listeners to see whether speaking clearly affects their own memory. "If you're rehearsing for a lecture and read the material out loud in a hyperarticulated way," Keerstock asked, "will that help you remember better?"
Berries, Orange Juice, Leafy Greens And Decreased Memory Loss
Drinking orange juice and eating leafy greens, berry fruits, and dark orange and red vegetables may be associated with a lower risk of memory loss over time in men, according to a study published in Neurology, the medical journal of the American Academy of Neurology. "One of the most important factors in this study is that we were able to research and track such a large group of men over a 20-year period of time, allowing for very telling results," said study author Changzheng Yuan, ScD, of Harvard T.H. Chan School of Public Health in Boston. "Our studies provide further evidence dietary choices can be important to maintain your brain health."
The study looked at 27,842 men with an average age of 51 who were all health professionals. Participants filled out questionnaires about how many servings of fruits, vegetables and other foods they had each day at the beginning of the study and then every four years for 20 years. A serving of fruit is considered one cup of fruit or ½ cup of fruit juice. A serving of vegetables is considered one cup of raw vegetables or two cups of leafy greens.
Participants also took subjective tests of their thinking and memory skills at least four years before the end of the study, when they were an average age of 73. The test is designed to detect changes that people can notice in how well they are remembering things before those changes would be detected by objective cognitive tests. Changes in memory reported by the participants would be considered precursors to mild cognitive impairment. The six questions include "Do you have more trouble than usual remembering a short list of items such as a shopping list?" and "Do you have more trouble than usual following a group conversation or a plot in a TV program due to your memory?"
Changes In Memory
A total of 55 percent of the participants had good thinking and memory skills, 38 percent had moderate skills, and seven percent had poor thinking and memory skills. The participants were divided into five groups based on their fruit and vegetable consumption. For vegetables, the highest group ate about six servings per day, compared to about two servings for the lowest group. For fruits, the top group ate about three servings per day, compared to half a serving for the bottom group. The men who consumed the most vegetables were 34 percent less likely to develop poor thinking skills than the men who consumed the least amount of vegetables. A total of 6.6 percent of men in the top group developed poor cognitive function, compared to 7.9 percent of men in the bottom group.
The men who drank orange juice every day were 47 percent less likely to develop poor thinking skills than the men who drank less than one serving per month. This association was mainly observed for regular consumption of orange juice among the oldest men. A total of 6.9 percent of men who drank orange juice every day developed poor cognitive function, compared to 8.4 percent of men who drank orange juice less than once a month. This difference in risk was adjusted for age but not adjusted for other factors related to reported changes in memory.
The men who ate the most fruit each day were less likely to develop poor thinking skills, but that association was weakened after researchers adjusted for other dietary factors that could affect the results such as consumption of vegetables, fruit juice, refined grains, legumes and dairy products. The researchers also found that people who ate larger amounts of fruits and vegetables 20 years earlier were less likely to develop thinking and memory problems, whether or not they kept eating larger amounts of fruits and vegetables about six years before the memory test.
The study does not show that eating fruits and vegetables and drinking orange juice reduces memory loss; it only shows a relationship between them. A limitation of the study was that participants' memory and thinking skills were not tested at the beginning of the study to see how they changed over the course of the study. However, because all participants completed professional training, they can be assumed to have started with relatively high cognitive function in early adult life. In addition, the study participants were all male health professionals such as dentists, optometrists, and veterinarians. Thus, the results may not apply to women and other groups of men.
Why Sleep Is Good For Your Memory
Researchers at the University of York have shed new light on sleep's vital role in helping us make the most of our memory. Sleep, they show, helps us to use our memory in the most flexible and adaptable manner possible by strengthening new and old versions of the same memory to similar extents. The researchers also demonstrate that when a memory is retrieved - when we remember something - it is updated with new information present at the time of remembering. The brain appears not to 'overwrite' the old version of the memory, but instead generates and stores new and old versions of the same experience.
The results of the research, carried out at York's Sleep, Language and Memory (SLAM) Laboratory, were presented in the journal Cortex. "Previous studies have shown sleep's importance for memory,” says lead researcher Dr. Scott Cairney of York's Department of Psychology. “Our research takes this a step further by demonstrating that sleep strengthens both old and new versions of an experience, helping us to use our memories adaptively. In this way, sleep is allowing us to use our memory in the most efficient way possible, enabling us to update our knowledge of the world and to adapt our memories for future experiences."
In the study, two groups of subjects learned the location of words on a computer screen. In a test phase, participants were presented with each of the words in the center of the screen and had to indicate where they thought they belonged. One group then slept for 90 minutes while a second group remained awake before each group repeated the test. In both groups, the location recalled at the second test was closer to that recalled at the first test than to the originally-learned location, indicating that memory updating had taken place and new memory traces had been formed. However, when comparing the sleep and wake groups directly, the locations recalled by the sleep group were closer in distance to both the updated location previously retrieved and the original location, suggesting that sleep had strengthened both the new and old version of the memory.
"Our study reveals that sleep has a protective effect on memory and facilitates the adaptive updating of memories,” added corresponding author Professor Gareth Gaskell of York's Department of Psychology. "For the sleep group, we found that sleep strengthened both their memory of the original location as well as the new location. In this way, we were able to demonstrate that sleep benefits all the multiple representations of the same experience in our brain."
The researchers point out that although this process helps us by allowing our memories to adapt to changes in the world around us, it can also hinder us by incorporating incorrect information into our memory stores. Over time, our memory will draw on both accurate and inaccurate versions of the same experience, causing distortions in how we remember previous events. The study builds on a research model created by Ken Paller, Professor of Psychology at Northwestern University, an eminent researcher in the field of memory and a co-author on this study.
Can Forgetting Make You Smarter?
For most people having a good memory means being able to remember more information clearly for long periods of time. For neuroscientists too, the inability to remember was long believed to represent a failure of the brain's mechanisms for storing and retrieving information. But our brains are actively working to forget, says a paper from Paul Frankland, a senior fellow in CIFAR's Child & Brain Development program, and Blake Richards, an associate fellow in the Learning in Machines & Brains program.
The University of Toronto researchers propose that the goal of memory is not to transmit the most accurate information over time, but to guide and optimize intelligent decision making by only holding on to valuable information. "It's important that the brain forgets irrelevant details and instead focuses on the stuff that's going to help make decisions in the real world," says Richards.
The review paper, published in the journal Neuron, looks at the literature on remembering, known as persistence, and the newer body of research on forgetting, or transience. The recent increase in research into the brain mechanisms that promote forgetting is revealing that forgetting is just as important a component of our memory system as remembering. "We find plenty of evidence from recent research that there are mechanisms that promote memory loss, and that these are distinct from those involved in storing information," says Frankland.
One of these mechanisms is the weakening or elimination of synaptic connections between neurons in which memories are encoded. Another mechanism, supported by evidence from Frankland's own lab, is the generation of new neurons from stem cells. As new neurons integrate into the hippocampus, the new connections remodel hippocampal circuits and overwrite memories stored in those circuits, making them harder to access. This may explain why children, whose hippocampi are producing more new neurons, forget so much information.
It may seem counterintuitive that the brain would expend so much energy creating new neurons at the detriment of memory. Richards, whose research applies artificial intelligence (AI) theories to understanding the brain, looked to principles of learning from AI for answers. Using these principles, Frankland and Richards frame an argument that the interaction between remembering and forgetting in the human brain allows us to make more intelligent memory-based decisions.
Making Better Memory-Based Decisions
It does so in two ways. First, forgetting allows us to adapt to new situations by letting go of outdated and potentially misleading information that can no longer help us maneuver changing environments. "If you're trying to navigate the world and your brain is constantly bringing up multiple conflicting memories, that makes it harder for you to make an informed decision," says Richards.
The second way forgetting facilitates decision making is by allowing us to generalize past events to new ones. In artificial intelligence this principle is called regularization and it works by creating simple computer models that prioritize core information but eliminate specific details, allowing for wider application. Memories in the brain work in a similar way. When we only remember the gist of an encounter as opposed to every detail, this controlled forgetting of insignificant details creates simple memories which are more effective at predicting new experiences.
Ultimately, these mechanisms are cued by the environment we are in. A constantly changing environment may require that we remember less. For example, a cashier who meets many new people every day will only remember the names of her customers for a short period of time, whereas a designer that meets with her clients regularly will retain that information longer. "One of the things that distinguishes an environment where you're going to want to remember stuff versus an environment where you want to forget stuff is this question of how consistent the environment is and how likely things are to come back into your life, " says Richards.
Similarly, research shows that episodic memories of things that happen to us are forgotten more quickly than general knowledge that we access on a daily basis, supporting the old adage that if you don't use it, you lose it. But in the context of making better memory-based decisions, you may be better off for it.