# Why memories can be wrong

> Each time you remember something you rebuild it, and the rebuild can pick up details that never happened.

Lesson 6 of 6 in [Why you remember and forget](https://learnfold.app/learn/memory/), a free course from Learnfold.

It's tempting to think of memory as a recording. Something happens, your brain saves it, and later you press play. This course has been chipping at that idea. You keep the gist and drop the details. Memories get reorganized while you sleep. This last lesson finishes the job. When you remember something, you rebuild it.

### A strange story, retold

In a book published in 1932, the British psychologist Frederic Bartlett described asking people to read a Native American folk tale called "The War of the Ghosts" and retell it, sometimes several times over months. The story felt odd to his English readers, and with each retelling it changed. It got shorter. Confusing parts dropped out. Unfamiliar details turned into familiar ones, and the plot bent toward what made sense in their own culture. Nobody was lying. They were filling gaps with what they expected.

### A single word

In 1974, Elizabeth Loftus and John Palmer showed people films of car crashes, then asked how fast the cars had been going. The question changed by one word. Some people heard "when they *hit* each other." Others heard "when they *smashed* into each other." The smashed group gave higher speeds.

A week later, everyone was asked whether they had seen broken glass. There was none in the film. People who had heard "smashed" were about twice as likely to say yes. One word, heard once, had become part of what they saw.



Switch the question between "hit" and "smashed", then check the original scene for glass. This source-checking exercise illustrates the distinction between an event and later wording; it does not recreate the study.

Later studies went further. With help from family members, researchers mixed a made-up story into true ones from an adult's childhood, about the time they got lost in a shopping mall. A minority, about a quarter in the first study, came to remember the invented event at least in part, sometimes adding details of their own.

### Outside the lab

In the United States, mistaken eyewitness identification played a part in most of the convictions later overturned by DNA evidence. Those witnesses were usually sincere. Their memories had been shaped by how lineups were run and by months of retelling.

Confidence is a shaky guide. The day after the Challenger space shuttle exploded in 1986, a group of students wrote down how they had heard the news. About two and a half years later, many told quite different stories and were sure of them. Some, shown their own handwritten account, still preferred the newer version.

There's a useful nuance. Recent research suggests that a witness's confidence at a first, fairly run lineup does carry real information. Confidence that grows later, after retelling and feedback, is much less trustworthy.

### Why your brain works this way

It looks like a flaw, but it's a trade-off. Storing the gist and rebuilding the details saves a great deal of space, and it lets you recombine pieces of the past to imagine the future. The cost is that each rebuild borrows from everything you know, including things you learned afterward.

For a learner, two habits follow. When something matters, write it down soon after it happens. And when you test yourself, check against the source, because retrieval strengthens whatever you pull out, mistakes included.

You now know more about how your own memory works than most people ever learn. Try it on the next thing you study.

### Rabbit holes

> How did the lost-in-the-mall study work, and what do its critics say about it?

> Why does a vivid memory feel so certain even when it's wrong?

> How should police run a lineup so eyewitness memory stays as reliable as possible?

Read online: https://learnfold.app/learn/memory/reconstruction/