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The Many Ways Our Memory Fails Us (Part 1)

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Recently, we discussed some of the net advantages of our faulty, but incredibly useful, memory system. Thanks to Harvard’s brilliant memory-focused psychologist Daniel Schacter, we know not to be too harsh in judging its flaws. The system we’ve been endowed with, on the whole, works at its intended purpose, and a different one might not be a better one.

It isn’t optimal though, and since we’ve given it a “fair shake”, it is worth discussing where the errors actually lie, so we can work to improve them, or at least be aware of them.

In his fascinating book, Schacter lays out seven broad areas in which our memory regularly fails us. Let’s take a look at them so we can better understand ourselves and others, and maybe come up with a few optimal solutions. Perhaps the most important lesson will be that we must expect our memory to be periodically faulty, and take that into account in advance.

We’re going to cover a lot of ground, so this one will be a multi-parter. Let’s dig in.


The first regular memory error is called transience. This is one we’re all quite familiar with, but sometimes forget to account for: The forgetting that occurs with the passage of time. Much of our memory is indeed transient — things we don’t regularly need to recall or use get lost with time.

Schacter gives an example of the phenomenon:

On October 3, 1995, the most sensational criminal trial of our time reached a stunning conclusion: a jury acquitted O.J. Simpson of murder. Word of the not-guilty verdict spread quickly, nearly everyone reacted with either outrage or jubilation, and many people could talk about little else for weeks or days afterward. The Simpson verdict seemed like just the sort of momentous event that most of us would always remember vividly: how we reacted to it, and where we were when we heard the news.

Can you recall how you found out that Simpson had been acquitted? Chances are that you don’t remember, or that what you remember is wrong. Several days after the verdict, a group of California undergraduates provided researchers with detailed accounts of how they learned about the jury’s decision. When the researchers probed students’ memories again fifteen months later, only half recalled accurately how they found out about the decision. When asked again nearly three years after the verdict, less than 30 percent of students’ recollections were accurate; nearly half were dotted with major errors.

Soon after something happens, particularly something meaningful or impactful, we have a pretty accurate recollection of it. But the accuracy of that recollection declines on a curve over time — quickly at first, then slowing down. We go from remembering specifics to remembering the gist of what happened. (Again, on average — some detail is often left intact.) As the Simpson trial example shows, even in the case of a very memorable event, transience is high. Less memorable events are forgotten almost entirely.

What we typically do later on is fill in specific details of a specific event with what typically would happen in that situation. Schacter explains:

Try to answer in detail the following three questions: What do you do during a typical day at work? What did you do yesterday? And what did you do on that day one week earlier? When twelve employees in the engineering division of a large office-product manufacturer answered these questions, there was a dramatic difference in what they recalled from yesterday and a week earlier. The employees recalled fewer activities from a week ago than yesterday, and the ones they did recall from a week earlier tended to be part of a “typical” day. Atypical activities — departures from the daily script — were remembered much more frequently after a day than after a week. Memory after a day was close to a verbatim record of specific events; memory after a week was closer to a generic description of what usually happens.

So when we need to recall a memory, we tend to reconstruct as best as we can, starting with whatever “gist” is left over in our brains, and filling in the details by (often incorrectly) assuming that particular event was a lot like others. Generally, this is a correct assumption. There’s no reason to remember exactly what you ate last Thanksgiving, so turkey is a pretty reliable bet. Occasionally, though, transience gets us in trouble, as anyone who’s forgotten a name they should have remembered can attest.

How do we help solve the issue of transience?

Obviously, one easy solution, if it’s something we wish to remember specifically, and in an unaltered form, is to record it as specifically as possible and as soon as possible. That is the optimal solution, for time begins acting immediately to make our memories vague.

Another idea is visual imagery. The idea of using visual mneumonics is popular in the memory-improvement game; in other words, associating parts of a hoped-for memory with highly vivid imagery (an elephant squashing a clown!), which can be easily recalled later. Greek orators were famous for the technique.

The problem is that almost no one uses this on a day to day basis, because it’s very cognitively demanding. You must go through the process of making interesting and evocative associations every time you want to remember something — there’s no “general memory improvement” going on, which is what people are really interested in, where all future memories are more effectively encoded.

Another approach — associating and tying something you wish to remember with something else you already know to increase its availability later on — is also useful, but as with visual imagery, must be used each and every time.

In fact, so far as we can tell, the only “general memory improver” available to us is to create better habits of association — attaching vivid stories, images, and connections to things — the very habits we talk about frequently when we discuss the mental model approach. It won’t happen automatically.


The second memory failure is closely related to transience, but a little different in practice. Whereas transience entails remembering something that then fades, absent-mindedness is a process whereby the information is never properly encoded, or is simply overlooked at the point of recall.

Failed encoding explains phenomena like regularly misplacing our keys or glasses: The problem is not that the information faded, it’s that it never made it from our working memory into our long term memory. This often happens because we are distracted or otherwise not paying attention at the moment of encoding (e.g., when we take our glasses off).

Interestingly enough, although divided attention can prevent us from retaining particulars, we still may encode some basic familiarity: 

Familiarity entails a more primitive sense of knowing that something has happened previously, without dredging up particular details. In [a] restaurant, for example, you might have noticed at a nearby table someone you are certain you have met previously despite failing to recall such specifics as the person’s name or how you know her. Laboratory studies indicate that dividing attention during encoding has a drastic effect on subsequent recollection, and has little or no effect on familiarity.

This phenomenon probably happens because divided attention prevents us from elaborating on the particulars that are necessary for subsequent recollection, but allows us to record some rudimentary information that later gives rise to a sense of familiarity.

Schacter also points out something that older people might take solace in: Aging produces a similar cognitive effect to attention-dividedness. The reason older people start feeling they’ve misplaced their keys or checkbook constantly is that the brain’s decline in cognitive resources mirrors the “split attention” problem that causes all of us to misplace our keys or checkbook.

A related phenomenon to this poor encoding problem is one called change-blindness — failing to see differences in objects or scenes unfolding over time. Similar to the “slowly boiling a frog” issue most of us are familiar with, change-blindness causes us to fail to see subtle change. This is the Invisible Gorilla problem, made famous through its vivid demonstration by Daniel Simons and Christopher Chabris.

In fact, in another experiment, Simons was able to show that even in a real-life conversation, he could swap out one man for another in many instances without the conversational partner even noticing! Magicians and con-men regularly use this to fool and astonish.

What’s happening is shallow encoding — similar to the transience problem, we often encode only a superficial level of information related to what’s happening in front of our face, even when talking to a real person. Thus, subtly changing details are not registered because they were never encoded in the first place! (Sherlock Holmes made a career of countering this natural tendency by being super-observant.)

Generally, this is totally fine and OK. As a whole, the system serves us well. But the instances where it doesn’t can get us into trouble.


This brings up the problem of absent-mindedness in what psychologists call prospective memory — remembering something you need to do in the future. We’re all familiar with situations when we forget to do something we clearly “told ourselves” we needed to remember.

The typical antidote is using cues to help us remember: An event-based prospective memory goes like this: “When you see Harry today, tell him to call me.” A time-based prospective memory goes like this: “At 11PM, take the cookies out of the oven.”

It doesn’t always work, though. Time-based prospective memory is the worst of all: We’re not consistently good at remembering that “11PM = cookies” because other stuff will also be happening at 11PM! A time-based cue is insufficient.

For the same reason, an event-based cue will also fail to work if we’re not careful:

Consider the first event-based prospective memory. Frank has asked you to tell Harry to call him, but you have forgotten to do so. You indeed saw Harry in the office, but instead of remembering Frank’s message you were reminded of the bet you and Harry made concerning last night’s college basketball championship, gloating for several minutes over your victory before settling down to work.

“Harry” carries many associations other than “Tell him something for Frank.” Thus, we’re not guaranteed to recall it in the moment.

This knowledge allows us to construct an optimal solution to the prospective memory problem: Specific, distinctive cues that call to mind the exact action needed, at the time it is needed. All elements must be in place for the optimal solution.

Post-it notes with explicit directions put in an optimal place (somewhere a post-it note would not usually be found) tend to work well. A specific reminder on your phone that pops up exactly when needed will work.  As Schacter puts it, “The point is to transfer as many details as possible from working memory to written reminders.” Be specific, make it stand out, make it timely. Hoping for a spontaneous reminder to work means that, some percentage of the time, we will certainly commit an absent-minded error. It’s just the way our minds work.


Let’s pause there for now. In our next post on memory, we’ll cover the sins of Blocking and Misattribution, and some potential solutions. We recommend re-reading Part 1 at that time, and then Parts 1 and 2 when Part 3 comes out. One easy fact about memory is that repeated exposure is nearly always a good idea. In the meantime, try checking out the book in its entirety, if you want to read ahead.