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Think back to when you were last at a family gathering or an annual work celebration. You run the event back in your mind, and it almost seems like you’re watching a movie. People tend to think that memories like this are stored in their brains like digital recordings of specific facts or events. But that’s not how memories are stored or retrieved.

The latest research on memory shows that memories are formed from particular neurons firing. Your brain is being rewired every time you form a memory. But your brain is also firing when you retrieve the memory. And every time you retrieve the memory, it may change based on new information and new memories. You re-create the memory when you retrieve it, so it’s subject to new neuron firings. Each time you retrieve the memory it changes a little more, especially for this type of memory.

Autobiographical Memories

People talk about memory as though all memories are the same, but there are actually many different kinds of memory. The example of the family reunion is an autobiographical memory. Autobiographical memories have to do with a specific event in your own life. These memories are subject to errors because they are re-created each time you bring them to consciousness from memory. Anything that’s occurred since you first created the memory may affect the original memory. For example, say you remember that your Aunt Kathy was at the family reunion last August, but actually she wasn’t at that reunion, she was at the holiday party in October. The memory has been altered and you probably aren’t aware of the alteration.

When people use your website to order clothes, you may not realize it, but they’re creating autobiographical memories. This means that how they remember the experience of using the website may not be accurate.

At the end of user testing of a product, I often ask people to talk about what they were thinking and what they experienced. It’s only been an hour or less, but even after that amount of time the memories of the experience are often different than the experience itself.

During a user test one participant commented that he didn’t like the purple colors at the website. Half an hour later, when we were discussing his experience, he commented on how much he liked the colors at the website. Another person I tested using online banking software to send a wire transfer was so frustrated that she alternated between using bad language and being almost in tears. Half an hour later she said she thought the site was really easy to use. I told her she didn’t have to say that, that she could be honest about her experience. She looked at me in confusion and said, “I am being honest.”

Strong Emotions Make Strong Memories

Another type of autobiographical memory is called a flashbulb memory. This kind of memory has a very strong emotional charge. If I ask you what you were doing on a specific random date 5 years ago you probably won’t remember much, and your memories may be vague, “Was that a weekday? If it was a weekday, I was probably working.”

However, if I ask you what you were doing when an emotional event occurred, for example, when a relative passed away, you probably have a very strong memory of where you were and what you were doing, because that memory was encoded with a strong emotional charge.

Ten Years Later

You may or may not be old enough to remember or have lived through the attack that occurred on the World Trade Center in New York City on September 11, 2001. If you were old enough and you were living in the US then your memories from that day probably are flashbulb memories.

Within a week of September 11, 2001, several researchers joined together (William Hirst, 2015) in the US and sent out surveys about the event. They then sent out follow-up surveys to the same people 11 months, 25 months, and 119 months (almost 10 years) after the event.
They found that people’s memories of the event (where they were, how they reacted, what happened during the event) changed a lot in the first year, and included many inaccuracies. After the first year the memories stabilized—meaning they didn’t change, but they still contained many inaccuracies. At the 10-year mark the memories remain stable, but still inaccurate.

The researchers also studied whether external events—how much people watched media accounts, talked to friends, or were personally affected by the events, for example—had an effect on the memories or their inaccuracies. They found no effect.

Most autobiographical memories activate the hippocampus in the brain. Flashbulb memories also activate the amygdala, which is where emotions are processed. Like autobiographical memories, flashbulb memories change a lot. People’s 9/11 memories are susceptible to alteration from news reports, and conversations with family and friends about that day. They’re a little different than alterations in regular autobiographical memories. Regular autobiographical memories continue to change over time. Flashbulb memories change a lot over about a year and then seem to resist change after that.

Can Memories Be Erased?

The 2004 movie Eternal Sunshine of the Spotless Mind is about a service people can hire to erase specific memories. When the movie came out there was speculation that this might be possible, but strong proof wasn’t in. Now, however, we know that it is possible to erase memories.

In fact, there are several ways to erase a memory. They’re all based on the idea that when you retrieve a memory you’re actually not retrieving an intact memory and playing it back—you’re re-creating the nerve impulses and brain activity you had when you first formed the memory. If you can disrupt the nerve firings, then you can’t create the memory—ever.

There are several ways to disrupt the firings:

  1. Particular proteins facilitate the process of forming a memory. If those proteins are stopped from being created, then you won’t form a memory. There are drugs that inhibit the protein.
  2. Xenon gas interferes with signal pathways in the brain, so if you breathe xenon gas while recalling a memory, it will erase the memory. Xenon gas is used as an anesthetic.
  3. Laser light can change genes and, in doing so, change a memory. The laser light turns genes on or off by stimulating or inhibiting proteins. Interestingly, this method of memory erasing, called optogenetics, is reversible. Amy Chuong (2014) now has developed a way of doing this that doesn’t require a brain implant. It can all be done with light outside the brain.


  • Because memory is easily changed, you can’t rely on what people say they were thinking or feeling while using a product. You have to observe what they do.
  • When you’re conducting user testing or feedback sessions with the target audience of your product, make a video recording of the testing or interview sessions since your memory may also be faulty.


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