Why do we forget books we’ve read? We ask an expert

Ever thought about a book you’ve read, and had no recollection of the plot? Or followed a recommendation to watch a TV show, only to find you’ve already seen it? We live in an age of mass content, with TV, books and films consumed at some of the highest levels in recent years. Could this be wreaking havoc with our ability to remember them? I asked Dr Sean Kang, a cognitive psychologist who specialises in memory: why do I keep forgetting the books I’ve read?

I did English at uni and it’s embarrassing how often a former classmate will mention a book I have no recollection of. My theory is it’s because I’m a journalist, and dealing with words all day is doing something to my brain.
Interesting intuition! One of the prominent theories of why we forget is interference. I’m going to assume you have read many other books?

Shucks, Sean, I think that’s the nicest thing any interviewee has said to me! But yes, I’d say so.
You probably read many books before and after the book your classmate is talking about. What happens is, when you’re trying to retrieve a memory of that book, all the information from other books interferes. Probably in your profession there’s even more opportunity for similar information to interfere.

Interesting! Is that why I still can’t quite remember the route to my in-laws despite having driven it a dozen times? I always thought it was something to do with using satnav.
Over time you will learn the directions. But relying on satnav is different; without satnav you’d need to chart your route in advance, and you’d pay close attention to every turn. That would help your learning.

It’s an active v passive engagement thing?
Absolutely. There’s also a new area of memory research that looks at our ability to remember stuff if we know the information is stored externally, for example, on a computer. The idea here is that our “working memory” – ie what we’re focusing on at any given moment – has a limited capacity. If we exceed that capacity by, say, paying attention to five things at once, we might try to offload some of that remembering to the external. And if we come to have an expectation that the information’s always at our fingertips, we might not encode the information in our mind very carefully when we do encounter it.

So we don’t remember stuff because we know it’s always there on Google – even Netflix.
I don’t necessarily see this as bad. It’s not that different from when someone gave you their number before mobiles. You could come up with a memory strategy to remember the numbers, or you could write them down, allowing you to use your working memory to focus on other things.

Or in the case of remembering birthdays, you could do as my husband does, and offload it to an external drive – me. I’m the USB stick. What does all this mean for our longest-term memories?
I’m not sure what you mean … researchers like me only use long-term and short-term. Short-term refers to information we hold on to for a few seconds. Long-term is anything we remember for more time.

Anything? Wow, my long-term memory must be absolutely massive.
It’s limitless. It’s not as if you learn one other new thing tomorrow, so you’re going to forget your friend’s name. It’s why, whatever our age, we always have the potential to learn.