There are a couple kinds of memory interference. Some vocab words for you here, one is called retroactive interference. This is the difficulty recalling an older memory, because you have memorized a similar item more recently and it feels like it's taking the place of the old memory. I'll give you an example. Let's say you're filling out an application and it's asking you for a previous place of residence, you can't remember the zip code.

Why is that? Your new zip code is interfering with recalling the older one. If you've never gotten a new zip code, let's say you had a zip code and that was it, you never had another zip code again. You moved, your new place had no zip code, you would probably still remember your original zip code.

But because you've been asked to learn a new five digit number that looks very similar, it comes up in similar context. Whenever you go and try to access that older memory, the pathways are diverting you towards your new number. Another example, this can be procedural. Let's say you used to be a skier, you switched to snowboarding.

When you try to ski for old time's sake, you make a lot of mistakes. Why is this? Your procedural memories of snowboarding are actually interfering with recalling your procedural memories of being able to ski. Young people are prone to retroactive interference, and this is because attention is biased toward new encounters and recent memories.

The other kind is the opposite, it's called proactive interference and this is the opposite. It's when it's difficult to recall new memories because a similar but older memory is more firmly entrenched. Example here, you're learning to play a piano piece, and one section is similar to a song that you learned years ago and you keep hitting the wrong notes whenever you reach this section of the new song.

That older procedural memory of the earlier piano piece is interfering, so aging and proactive interference. Older adults are more likely to experience proactive interference. Overall, I will say that memory difficulties for older adults are more amplified, regardless of whether it's retroactive or proactive. But proactive in particular, a very heightened type of interference, a pattern very commonly found among older adults.

Why is this? The memories that were formed earlier on for these people were encoded when the brain was younger, so they're better encoded and also older adults reflect a lot more on the past. They have a bias towards memories, their minds live more in the past. An example of this is, let's say you've been with current boyfriend or girlfriend for a year, but your aunt keeps referring to him or her by the name of your ex from your senior year of high school.

This is proactive interference. Last thing I want to go over is source monitoring. This is attributing a memory to a particular source, and that's whether it is correctly attributing or not. There are two kinds of source monitoring, there's internal and there's external. One example, let's say I have a memory of going to London, but through source monitoring, I know it was part of a dream.

It didn't really happen, the source of it was my dream. This is an example of internal source monitoring. In internal source monitoring, I'm differentiating between a memory that originated from my own mind, versus a memory I derived from something that actually happened out there. Then there's an external example, so I learned long division from Mrs Miller, my fourth grade teacher.

This is an example of external source monitoring, because I'm remembering specific details about when and where I learned something that happened out there. Wasn't third grade, wasn't fifth grade, wasn't this other teacher. People's assumptions about the source of a memory are often wrong and the mistakes that people do make tend to reflect preexisting biases and attitudes. Another example for you.

Let's say you really respect your financial advisor and when someone says, where did you get the idea to open up an IRA such a young age? You say it was from your financial adviser. In fact, the idea came from reading an online blog, but youR memory has been altered by your favorable attitudes. Now I will put in the disclaimer here, if you really do have a super strong memory of a source, it probably really did derive from that particular source.

But if there's some fuzziness, some confusion, if the memory of where something was learned is not totally clear, people fill in the gaps and they fill in the gaps in ways that fit their preexisting beliefs. As people age, their source monitoring contains more errors. Questions somebody might be asking themselves, did I tell my husband to put the check in the mail, or was I just thinking that to myself?

This is an example here of internal because she's trying to decide whether it was something that really happened outside or whether it was something that happened in her own mind. Or did I already tell my neighbor that funny joke, or did I tell it to my other neighbor? Maybe nobody has heard it and I should go ahead and tell it again.

These are common sources of confusion. Confusion about the source, and here of course, this is external monitoring. Not only does source monitoring become a problem, in general overall, but it becomes even more prone or vulnerable to biases. Let's say a man in his 70s has formed the belief that his granddaughter is the artsy one and his grandson is the athletic one.

A visitor comes by, notices a photograph of a sunset on his fridge and asks him who took the picture? The grandfather respond, my granddaughter, with full conviction that it was her. Let's say it was really taken by his grandson, however, this particular person has misattributed the source of the photograph in ways that align in accordance to his beliefs.

Now let's end with a practice problem. The inability to form new, long term memories might be caused by which, A external source monitoring? B, Retrograde interference? C, Proactive interference? Or D Anterograde amnesia?

Pause the video if you'd like. The answer here is D. This was a little bit tricky because I didnt go over this in full detail, but I am hoping that by the process of elimination, you are able to come to that. First of all, if you are doing process of elimination, B would be the first one to go.

Retrograde interference is when new information is actually taking the place of, or interfering with older information. External source monitoring, this is just trying to remember where something came from. It has nothing to do with formation, it has nothing to do even really with the retrieval of the memory.

It's about differentiating between different places or environments in which this memory might have originated, so we can cross out A. In this case, we'd be left with proactive interference or anterograde amnesia, and how do we know it's D and not C? Again, the key word here is form. In proactive interference, it is difficult for a person to retrieve the newer information, because the older information is vying for the attention.

However, that long-term memory was formed there. So that's why I was saying that in this case, D, I was asking you to take a little bit of a leap, because when we talked about anterograde amnesia, I mentioned that it's hard to retrieve memories about an event that occurs following an accident or injury. It's also sometimes difficult to even form new memories in the first place.

One last thing I want to say about that, is that it also just brings to light, and this is the end of this series on memories. One of the most important things I hope you take away from this is that if something was stored in your memory for more than 30 or 45 seconds, it is in your long-term memory. That grandfather who had the picture on the fridge, if you'd asked him earlier the same day that picture was given to him, who took the picture?

That Grandfather would know, so it was in the long-term memory. The problem was that over time, the retrieval started to have errors in it.