CHAPTER ONE

What Is Memory, and How Does It Work

In a laboratory at the University of Berlin in Germany, in 1879, a young scientist named Hermann Ebbinghaus struggled alone to memorize long strings of nonsense words, such as TIR or XUQ. Remembering words that had meaning would’ve biased the research, as Ebbinghaus could have potentially relied on his own knowledge and associations with the words’ meanings in order to recall them. To further ensure the test was completely random, he wrote these nonsense words on slips of paper, mixed them together, and drew them out of a container one at a time, creating lists of syllables with no specific pattern.

Ebbinghaus developed this research method in an attempt to prove that memory could be studied, even though his peers believed it was impossible. Using himself as the lone subject, Ebbinghaus read through several of the words and then attempted to recite them. He determined how many readings were required to memorize the string, based on the string’s length and the time lapse between readings and recitations. What he concluded was that when a person did not attempt to retain new information, forgetting increased over time—known famously as the “forgetting curve.” Ebbinghaus is also the father of the learning curve.

The published study shed the earliest light on an elusive function of the human mind: its ability to remember. Ebbinghaus’s resulting 1885 book, Memory: A Contribution to Experimental Psychology, launched a new field of scientific interest, one that led to a stronger and more cohesive understanding of memory and the ways that it can be influenced, preserved, and improved.

Since Ebbinghaus’s day, the study of memory has included everything from neuroimaging to studying the effects of stress, alcohol, sleep deprivation, inactivity, caffeine, artificial sweeteners, vitamins, minerals, Google, and many other influences on how we form memories and remember information.

Even before Ebbinghaus sat alone in his lab with his strings of nonsense syllables, philosophers and scientists puzzled over the workings of the human memory.

More than 2,300 years ago, Aristotle postulated that human beings are the sum of their experiences, born as blank slates onto which all of their memories are etched from birth to death. He referred to the memory in terms that became known as the “storehouse metaphor,” one that stood as the standard definition of memory for many centuries. Not until the Greek poet Simonides stumbled on a new theory of memory retention, the method of loci, did the perception of what memory is develop beyond the basic idea of storage and retrieval to the ability to associate objects with the place at which they appear. (For more on the method of loci, see Chapter Eight.)

Research since the days of the Roman Empire continued to reveal bits of information that expanded scientists’ understanding of human memory, with Ebbinghaus making the most significant contribution. The field did not truly take off until the 1940s, when technology allowed researchers to determine what actually takes place within the brain. The renowned scientist Karl Lashley used research on rats navigating mazes to determine that many parts of the brain are involved in storing and accessing memories.

The Canadian researcher Donald Hebb made a breakthrough in the same era, theorizing that memory encoding takes place when connections are formed between neurons and synapses. Scientist Eric Kandel confirmed this theory in the 1970s through his Nobel Prize-winning research with snails. He learned that while short-term memory involves transient changes in the connections between cells, long-term memory requires lasting changes that come from the growth of new connections between synapses and neurons.

While an enormous body of research now exists, memory—like the brain in which it takes place—remains only partially understood. To improve your understanding of the definition and workings of human memory, it is helpful to consider the observations between disciplines.

The Medical Perspective

Medical doctors view memory primarily from a biological perspective, speaking in terms of parts of the brain and neurological processes. You may be surprised to learn that information about brain activities that form memories is fairly vague, even in our scientifically and technologically advanced times.

Scientists know that memory creation begins with a biological process called encoding by way of the five senses: sight, sound, touch, smell, and taste. The general definition of the word “encode” is to convert messages; therefore, what you experience through the senses is converted into a memory. For example, think of a person who means a great deal to you in your life—perhaps your father. How do you perceive him? Chances are you remember what he looks like, the sound of his voice, and the smell of cologne you associate with him. You may recall the feeling of a particular shirt against your fingers, or the strength of a hug. You also may remember how your father makes you feel emotionally: the pleasure of a shared joke or a loving glance, or the anger of a confrontation. Each one of these perceptions are separate until they travel to the part of the brain called the hippocampus, where they are combined together to form a complete memory of this person.

According to researchers who study the brain, the hippocampus—located deep in the center of the brain, under the cerebral cortex—acts as a sort of biological scout, determining which perceptions are worth saving as memories and which are not. After this first screening, the hippocampus determines what short-term memories it should retain and encode into long-term memories.

The hippocampus does not actually store the memories, however. All of these disparate perceptions break down into bits of information that are stored in different parts of your brain. Meaning that while you might not be thinking about your father in a particular moment, the smell of a passerby’s Old Spice will trigger the part of the brain that retains smell and the association of Old Spice with your father. What results is not just a memory of the smell but also a cohesive memory of your father.

How the brain takes a perception from one part of the brain and joins it with another to then bring all the sensory perceptions together for a full long-term memory relies on the brain’s biology. Nerve cells connect with one another through passageways called synapses, bridges over which electrical impulses can travel via neurotransmitters. Using these synapses and neurotransmitters, your nervous system passes the scent of cologne to one area of your brain, the feel of a shirt to another, and the sight of your loved one to a third area.

These neurotransmitters then attach themselves to dendrites, the parts of the nerve cells that retain memories at the other end of the synapse. The connection creates links that become part of the brain’s ability to recall information at random. Your brain may contain more than one hundred trillion links like these, a vast neural network that allows you to function in a world filled with potential memories. Proteins in your brain make the communication among brain cells possible, and they also determine the lifespan of brain cells and repair your DNA. How exactly the hippocampus retrieves all of these bits of information from different areas of the brain and reassembles them into one memory remains one of the great mysteries of modern science. Suffice it to say that the human brain serves as the most complex random-access memory computer in existence.

What we do know is that these links can change as required, creating networks that serve to process particular kinds of information, and then shifting to process something different. This is what scientists call plasticity, the brain’s ability to shift these transmissions whenever new connections are needed—making it possible for the brain to work around a damaged area or to become stronger through continued use in a certain way.

Through the techniques described in this book, we will take advantage of the healthy brain’s plasticity to strengthen the bonds between dendrites and synapses, allowing you to boost the functioning and flexibility of your memory.

The Psychological Perspective

Psychologists explore memory as a function of information processing, examining its sequence of maintaining and accessing impressions and experiences. They define memory as the mind’s ability to encode, store, and retrieve information.

Encoding takes place when you are presented with information and take it into your memory. For example, when you read a story in the newspaper and you want to remember the details, your mind absorbs that information in one of three ways: visually, acoustically, or semantically.

• Visually: Your mind may create a “mental picture” of the information. If the story involves a car accident, for example, your mind instantly creates an image of the accident—even when there is no photo in the story—and you store that image automatically to remember the story, so you can repeat it to your spouse later. You don’t need to think, “Wait, let me get that picture in my mind,” because the encoding process happens on its own.
• Acoustically: When you meet someone new, do you repeat their name aloud after they’ve told it to you? You are creating an acoustic memory, a way for your mind to hold on to the name so you can recall it later. Now that you know what you’re doing, you will catch yourself repeating telephone numbers, addresses, other numbers and codes, new words, and the names of various objects to help you commit them to memory.
• Semantically: Giving information its own meaning or context is considered a way to encode using semantics. For example, when you think of your child’s graduation from high school, that moment has considerable emotional meaning and context. Recalling that feeling brings the memory back vividly, with all of its personal significance.

Once your brain encodes, or converts, the information, it uses short-term and long-term memory to determine which information can be used and discarded, and which should be retained for a longer time—or for a lifetime.

Using your short-term memory, your brain can select information, process the information it selects, and complete complex calculations or find more subjective solutions. For example, your brain can read the calories, fat, and fiber content on a box of cereal and remember their facts long enough for you to record them into your food journal. By the time you pour the cereal, the detailed information vanishes from your memory. Generally, short-term memories last only a few seconds.

Long-term memory takes the information gathered by short-term memory and stores it for use at another time. Many long-term memories last a lifetime, especially those formed early in life. It appears that human beings can retain an unlimited number of memories, creating as many clusters of information—life experiences, people, songs, events, and countless others—as their lives require.

Studies in the psychology of memory indicate that acoustic encoding is the most effective method for committing information to short-term memory, while semantic encoding carries the information into long-term memory.

Finally, the mind has the capacity to retrieve information stored in memory, no matter how long ago the memory was stored or what kind of memory it may be. How the brain retrieves these memories depends on whether they are stored in short-term or long-term memory.

Studies have shown that short-term memory is retrieved sequentially. Think about how this works: When you have to remember the fifth thing on a list of ten things, how do you recall what the fifth thing was? Chances are that you count through the first five things, perhaps even using your fingers to count them off. You need the whole list to remember these things in sequence.

Long-term memory, on the other hand, allows you to remember things according to the other things with which you associate them. For example, how often do you find yourself standing in the middle of your living room, trying to remember why you are there? If you retrace your steps to where you were before you entered the living room, the memory of what you wanted suddenly pops back into your consciousness. Your brain associates the thought of the book you left on the coffee table with the room you were cleaning when you thought of it.

Meeting of the Minds

Scientists on both the medical and psychological sides point to the cognitive revolution of the 1950s and 1960s as a transformational time in memory research. During this period, the two points of view converged to create a new field called cognitive neuroscience, spurring the work of new researchers, including George Miller, one of the best-known experts on short-term memory. Miller’s paper on short-term memory, “The Magic Number Seven, Plus or Minus Two,” was the result of an extensive review of decades of psychologists’ research. Miller’s conclusion—that people generally can remember a cluster of seven digits or words in sequence, plus or minus two—led to the modern-day seven-digit telephone number.

Since the 1970s, a number of researchers have explored methods for improving memory, and several methods have proved to be successful both in controlled research settings and in everyday practice.

One of the leading teams in this area comes from the world of special education. Margo A. Mastropieri and Thomas E. Scruggs, professors at Purdue University, researched ways to facilitate learning and memory in students with learning disabilities. Their work with mnemonic devices, including association and visualization—discussed in detail in Chapters Five and Six of this book—provided students with the ability to retrieve factual information to answer questions on tests by connecting the new information they studied to a keyword already embedded in their long-term memory. For example, a student remembered the capital of Florida by associating Florida with “flower,” and Tallahassee—the state capital—with “television,” and then picturing the flower on top of the television. Students who memorized information using this method performed better on comprehension tests.

Studies throughout the 1990s and 2000s led to increased knowledge about memory function and improvement. For instance, research produced results in protecting against the development of Alzheimer’s disease in older adults. Among the strategies are using commercial brain-training games (in this case, Brain Age and Tetris), increasing regular exercise in older adults, and using mentally stimulating activities like crossword puzzles and discussions about politics and current events. Modern research has also found that the use of a computerized memory program can help victims of traumatic brain injury improve their short-term memory function. One recent study showed that physically fit children perform better on memory tests, while another concluded that learned information remains in the brain even though a person can’t recall it readily.

What do all of these recent studies tell us? Many of the memory improvement methods in use today actually have the potential to produce results, if used judiciously. The best and most proven of these have been selected for inclusion in this book to provide you with an objective overview of the methods available to you. Once you understand how these methods work, you can implement them on your own.