Jackson Pollock, Number 48, 1949. image from Wikiart, under Fair Use conditions
When I was a practicing neuropsychologist, the single most common concern in patients, or their families, was memory loss. Any decline in memory function had implications for their ability to work, drive, or function independently. So much in life was threatened if memory did not function properly.
When thinking about memory, we usually think about the front end of it, which is learning, and the back end of it, which is recall. Those two processes are the conscious parts of memory. We use them intentionally. Other memory activities, in between learning and recall, occur automatically and unconsciously.
What we know about the mechanics of learning and recall comes largely from testing people who have brain problems which might have affected memory, or who report poor memory that might mean brain problems. Memory testing is a regimented affair. The phases of learning and recall in these situations are controlled. I am going to read a story to you and when I am done I would like you to tell me as much as you can remember is just one way to approach it. The controlled conditions allow for a careful parsing of the complexities of memory. There are many ways for memory to go wrong.
In a formal exam, the neuropsychologist will test visual memory, memory for words, unrelated words and stories; learning by rote, with a little context, in a lot of context; recall after no delay, after a delay with distraction, after a long delay; straight recall, cued recall, and recognition. There are tests in multiple cognitive domains: for words and language; for vision, hearing and motor sequences. At the end there will be many data points that together outline memory function in that one person.
Such an exam will speak to the integrity of the brain. Are the memory systems functioning within normal, or individually acceptable, limits? Are there any patterns that point to a specific disorder or lesion location? Is there a history of change that will define an illness?
But people are more than just a well functioning brain. When it comes to memory, what people learn from an experience and what they later recall is nowhere near as predictable as formal testing would suggest. The mechanisms of memory do not dictate what people will choose to learn, remember and forget.
The question moves beyond how a brain builds memories to how the mind decides what it needs to remember and what it can forget. These decisions are personal and variable. As the judicial system has learned, eye witness recall is highly inaccurate. Accounts vary amongst witnesses, and few of them are at all accurate. Ten people observing the same event simply will not give ten consistent reports.
The neuropsychology of memory shows us what methods are available when we want to learn something, but everyday experience is not just about the cognitive tools we have at our disposal. An individual spontaneously filters for understanding, and adds their own context and meaning. Some elements of an event or the news may not fall within the personal body of knowledge and be set aside. Some pieces will fit into someone’s range of experience and world view, in which case they are slotted in and retained. Some bits will be thought about and considered, to eventually be kept or discarded. At this stage acquiring information becomes subjective.
A memory is formed in a period of time that falls between between learning and recall. It is an automatic and unconscious phase in which information is encoded into long term memory. The time can vary from as little as 20 minutes to an overnight period of sleep. Automatic mental processing goes on, beyond awareness, during that formative phase. One result is that whatever was previously learned, such as how to ride a bike or a chapter of physics equations, has become consolidated. The elements are linked together and the whole set takes on a smooth, integrated character.
This level of processing adds a valuable degree of integration. What we do retrieve it from memory is no longer just single pieces, movements or facts; the information now comes together as a whole. A subjective overlay of connections and emotions binds the parts together. This is the personal context into which new information is placed. The new information takes on a form that is useful for the individual. It can serve a purpose. It is the personal knowledge of how things work, and how to do things. The end result is understanding how pieces fit and work together, such as how families cooperate; how governments fall; how to ride a bike. Because this is a subjective and personal process, inaccuracies can and will exist. The most important thing for a newly formed memory is that it works for that person.
You can be taught observation and facts, then trained to organize information in systematic ways. To the historian, it is the narrative that binds facts and explains events. To the chemist, it is organizational strategies for elements and the dynamics of chemical reactions. But spontaneous learning and memory is more subjective, less constrained and less predictable. This is our window into how the mind takes up the tools of memory and uses them for individual purpose. Memory in the individual case looks more like a Jackson Pollock painting than a sheet of schematics.
Whatever form information takes, there is a memory system to hold it. There are specific brain mechanisms devoted to remembering the name of something, its location in space, the sound of it, the way it moves and the way it made you feel. That there are so many systems devoted to memory formation tells us that holding on to information of all kinds is a mental priority.
The role of unconscious processing, and very specifically memory processing, is to build an internal version of reality that is so reliable we will accept it as true. We can reliably base future actions on what we believe to be true. Accuracy is desirable but being able to rely on the personal version of what is real is actually more of a priority. You see this every time someone argues with the facts of a matter. They know what they know.
What happens at this spontaneous, automatic and largely unconscious level of memory is all about what is useful to that individual, at that point in time. At an earlier age, we cast a wide net for learning new things. Much information is absorbed, and many memories formed. The focus changes with experience. What is retained in memory and what is discarded is personal. Memories are formed to serve the individual purpose. They build and reinforce a representation of reality, a personal world view. On one level, memories are valuable because they are adaptive. The better you understand the environment around you, the better your odds are of survival. On another level, the budding world view guides personal choices.
Why this messy re sorting, networking and cross connecting? Why not just store the facts, clean and clear, so we can retrieve them later like a computer?
The consolidation step makes information accessible. So many cross references means there are many avenues to search for information. For example, if someone asks you what you ate for dinner last night, you might think about with whom you ate dinner; whether you went out or stayed home; which day of the week it was, if Tuesday-and-spaghetti are a standard at home. Perhaps you will recall stopping at a market on the way home, or an hour in the garden pulling beets. Maybe a residual feeling of satisfaction will connect to previous good meals. I like apple pie after roast. There are many, many ways to arrive at the memory of the meal you ate the night before.
Consolidation also makes information more useful by placing it in a context that gives it meaning. The context also confers priorities and utility. When you understanding what a piece of information means, you can then work with it.
The key is the attribute of need or importance that comes with context. This is the organizational pivot point that prioritizes what will be learned and what will be ignored. The task in learning is to decide, Is this piece of information worth keeping? The task in recall is, what do I need to remember right now? A good cross referencing system and multiple associations allows us to decide if there is a place for the new, and to quickly access the old.
The decisions matter, because memory takes time and energy. It is necessary to prioritize what information merits the effort. What you learn has to serve a purpose. It underlies the response you hear from adolescents in school: I am not doing this. I will never need to know geometry. Having a purpose, a reason to learn something, drives students like nothing else.
Single pieces of information are not just facts to be filed in a mental drawer. They are building blocks, consolidated into an end product, knowledge about the world. When information turns into knowledge it is in a form that has already been prioritized and arranged for quick access. Memory is not formed randomly; it is organized toward purpose.