Eli5: Why do we forget things but people with eidedic memory can remember everything?



I can forget what I studied for an exam, but others can remember. Then you have people with eidedic memory that don’t forget at all.

In: Biology

Nobody has a perfect memory. There’s natural variation in how good memory is, but above a certain level you’re seeing a learned skill of associating things with other things and forming patterns to make it easier to remember stuff.

If you want to get better at it, look up the Roman Room method, also called a memory palace or the method of locations. Sheer practice also matters.

That’s not exactly what eidetic memory is. Eidetic memory refers to people who remember things as if it was happening right in front of them. So the memories you do have are insanely vivid and detailed, but can still be inaccurate or lost.

I believe I have it. I definitely don’t remember everything, but it’s rare that my memory is ever wrong or lacking in detail. Vocabulary tests used to be the literal easiest thing possible for me. I wouldn’t need to look at my notes like everyone else right before a test, because the image of the definitions was in my memory. But I sure as hell don’t remember the page of definitions today.

One of the primaries directives of all human organs is to consistently reduce unnecessary effort, in order to optimize energy consumption. The brain is no exception, so it’s important for a healthy brain to routinely cut out low-priority information. We only forget things because the brain is designed to optimize for thoughts that either happen frequently, or are considered a high priority for survival.
So someone that doesn’t forget things might have been at a disadvantage in the scarce hunter-gatherer world our species originally evolved in, simply because their brain consumed too many calories, or because it optimized for redundant memorization rather than survival.

Actual eidetic memory involves being able to hold very detailed visual images for a brief period of time. If I show you a picture of a city street and then take it away, it’s very unlikely that you’ll be able to tell me what color dress the young lady waiting for the bus was wearing. However, a person with eidetic memory could still ‘see’ the image and focus in on that one particular detail (at least for a time).

The magical kind of memory you’re talking about doesn’t exist.

In terms of remembering, your brain is just a large correlation engine. This means you’re much more likely to remember what is highly correlated with other elements of your memory. A musician might be able to remember how to play thousands of songs, but would struggle to remember their phone number. Not only can they contextualize all of those songs within the data of all the other songs they know, but they constantly reinforce those memories by playing the music in settings which add multi-sensory cues. In contrast, they can’t remember their phone number because the only time they ever use it is when they fill out forms asking for it.