When I recently discussed a meeting that
had been held two weeks earlier with the attendees, I was not surprised that
there was no agreement about the contents and conclusion.
Each person was
convinced that the others had poor memories and that his recollection was more
accurate. No doubt, each of us had a similar experience.
the meeting as a brainstorming session to explore ideas, while others thought
it concluded with an unambiguous decision. A manager might be remembered as
promising a raise if a certain goal was met, while he might remember the idea
only as a possibility.
Why does a
shared event result in such wildly different memories of the event? This is not
a trivial question.
remember the childhood game of “telephone,” in which the first person whispers
a story to the second person, who whispers the heard story to a third person
and so on. Everyone gets a good laugh when the story at the end of the chain is
compared to the story that started the sequence.
starting and ending story appear to be completely unrelated. On each retelling,
new errors and changes are introduced. Even over a one-minute interval, memory
fails: You cannot articulate accurately what you just heard.
have been teaching a course on cognitive science, and in preparation for the
classes, I have been reviewing the most recent research on what we are as a
On the playground or in the office, each of us is
experiencing our very own version of a story.
dramatic conclusion is that our self image of what it means to be human arises
from a belief as to what we should be rather than
what we are.
engineers know better, we like to think of our auditory memory as a sound
recorder and our visual memory as a camera. Nothing could be further from the
analogies are compelling but misleading. The brain is not a computer; the
visual memory is not a camera; the auditory memory is not a recording device.
BAD WEATHER PREDICTION
Our brains were not designed to be
accurate; rather, they were designed to keep our ancient ancestors alive in a
ancestors had only a few goals: find food, avoid being eaten and produce the
next generation of children. Logic, rationality and an accurate memory had
nothing to do with survival.
our memory of danger had more survival value than overestimating safety. Hence,
weather forecasters tend to predict the next big storm as massive, even if it
turns out to be nothing more than a little rain. Survival is enhanced by
overreacting to danger and underreacting to safety.
lifetime, our eyes and ears are presented with more than 50,000 billion bits of
information. Even if that information could be recorded, how would our brain
find the useful information when needed? It’s hard enough for me to find a
document on my computer from last year. The issue of memory is more about
storing it in a way so that it is available when relevant.
The brain has to break an experience
into “relevant” pieces and then connect each piece in such a way that you can
find the useful pieces in a fraction of a second. Something has to give;
accuracy is sacrificed for retrieval efficiency.
When you daydream,
you are actually watching the brain follow associated connections of memory
fragments. You think about an upcoming vacation, that links to last year’s
vacation in the mountains, which links to a sudden storm, which links to the
hole in your roof, which links to the fallen tree, which links to your damaged
car, which links to the current price of gas, which links to the lack of an
expected raise, and so on.
The brain has its
own retrieval logic. The same process takes place in a serious professional
research has shown conclusively that events are decomposed into thousands of
“relevant” components, each of which is linked to an array of associated
experiences. When you recall an event, the brain has to reassemble these pieces
into a coherent picture. Essentially, a memory is a re-creation, not a
retrieval. You may not like this view of the human brain, but you were not the
designer of humanity.
sense of memory, we have to start with a broad definition: Any experience that
can influence future actions and decisions is effectively “remembered.” How it
influences the future is not simple. Recall is only one manifestation of
two basic categories of memory: declarative and non-declarative. In the former
category, the recall can be described in words, which is why this kind of
recall often is called semantic memory. Within this category, we have factual
memory and autobiographical memory. Factual memory is simply what it says, such
as: Our country has 50 states. Autobiographical memory is a personal
experience, such as: I had eggs for breakfast.
actually arise from a personal experience. The first exposure might have been
during a class when you were 6 years old. The biographic component eventually
gets discarded. One can remember the “fact” but not the context and assumptions
when it was learned.
Non-declarative memory is the more
interesting case, because it results when experiences change the brain so that
the information can be used in a high-speed non-conscious way. You may not be
able to describe every turn in driving home each day, but you can do it while
thinking about other things. The route is remembered experientially but not
declaratively. You can drive home easily, but you may not be able to accurately
describe each turn. Similar, you cannot readily describe how to ride a bicycle
or give a lecture or hold a conversation or prepare a meal.
memory is central to all forms of information storage, yet it is always
non-declarative. You may remember that you were angry
but you cannot remember feeling angry. A remembered
face cannot be put into words. Pain (or any form of social discomfort) can only
be described as a metaphor, as in “his comments made me sick to my stomach.” We
give facial displays and tone of voice meaning, but our memory of this kind of
information is far from objective.
THE WEAKNESS OF LANGUAGE
There are a large number of lectures by
famous scientists on the subject of memory. Some of these are brilliant and
require no background on the subject. YouTube, for example, has several
lectures by Daniel Kahneman, a Nobel laureate notable for his work on the
psychology of judgment and decision-making. You can also find great discussions
about false memories presented by Elizabeth Loftus. (Kahneman and Loftus).
Putting a memory
into language also suffers from the weakness in language. Most verbal
expressions are metaphors, narratives using analogies to other shared
experiences. In fact, if you describe a memory to a friend, you will notice
that it is nothing but a story that is consistent and meaningful without any
way to validate its accuracy.
This issue is central to our legal
system. Because there have been so many cases of faulty eyewitness reports that
resulted in long prison sentences, the problem of memory has been studied
event is described multiple times, each recall is actually the previous recall
instead of the original. If I tell my spouse about my day during dinner, and
tell the story again the next day, the second retelling is closer to the first
retelling than to the actual event. Memories evolve and get changed. For this
reason, the legal system places more credibility on a written version of events
done shortly after they happened. They call this process memorializing.
executives use contracts as a way of stating explicitly what was agreed to
without depending on memory. While a verbal agreement is legal, the courts
dislike this kind of evidence. For this reason, any meeting that is worth
having should also have a written summary distributed to the participants. They
are more likely to recognize errors and omissions before their memories decay
to the point of fantasy.
conclusion of this discussion on memory is humility. Just as we look at a
technical system as having properties, so too must we look at our brain as
having a matching set of properties. In both cases, these properties arise from
the way in which the system functions. We all need to become experts on the
properties of the human brain, ignoring any assertion that we are what we want
to be, or should be.
Blesser is director of engineering for 25-Seven Systems. Contact him at