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Forgetting: Decay and Interference – Memory (PSY)

by Tarry Ahuja, PhD

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    00:01 So memory decay can result in failure to retain stored information as well.

    00:05 So, So as things decay over time if you’re not accessing them, you’re not going to be able to retain them.

    00:13 You’re not going to be able to recall them.

    00:15 Okay? So, retention interval is the time since the information was learned.

    00:19 So, So, when you learn something to -- as long as it lasts in your memory, would be retention interval and this can be variable.

    00:28 So the longer this interval is, the more likely this info will be forgotten.

    00:31 So if you don’t access something often, you’re going to lose it.

    00:35 That makes sense, right? And the more often you do access it, the better because it’s getting reinforced and it’s staying.

    00:42 The more you access something, the better its retention.

    00:45 So the most rapid loss of info occurs within the first few days.

    00:48 So if you learn something and then you don’t revisit it, it’s gone.

    00:51 And the moment where you’re trying to remember, you’re like, “Oh, I got this.” And then it’s gone.

    00:55 Now, you, right now, sitting at your desk, trying to remember all the stuff that you’ve been studying here for the MCAT, it’s great that in the moment when you’re studying, you say, “Yup, I totally understand social behavior. I got it.” And then you don’t access it again until you write the exam, you’re not going to remember as much as opposed to revisiting it.

    01:15 And by revisiting, it doesn’t mean necessarily relearning the whole thing but just simply reading passages over or reintroducing yourself to a concept that you’ve learned prior will strengthen its retention.

    01:26 Okay? Proposed mechanisms behind decay and loss include the loss of memory specific brain cells which can happen.

    01:35 But more specifically, for us and kind of what we’re talking about today, it’s more around the weakening of the associations between nodes.

    01:41 So, if we don’t access and if we don’t strengthen the connections between nodes, the chances are that you will lose and it will decay, and then that memory is no longer there.

    01:54 So here’s some what we call forgetting curves.

    01:58 And what you see is, we’re looking at percentage of data remembered on the Y axis.

    02:02 And on the bottom, we’re just looking at the times that you have repeated or access yourself to the information.

    02:09 So very first time you see it.

    02:11 Your percentage of data remembered right away will be very, very high, but very quickly that decays.

    02:17 Okay? So that’s where you see the dash line and that’s the memory loss.

    02:22 It’s being decayed.

    02:24 Now, if you move over, if you move over one point, you have second repetition.

    02:29 It goes right back up to 100% memory.

    02:32 You’re recalling it.

    02:34 And then that also quickly decays.

    02:36 A third repetition and then a fourth.

    02:39 Now, what you notice is, a couple of things, one, the amount of decay that happens is a lot less.

    02:45 So, by the time you get to the transition between third and fourth, even at its worst case scenario, it’s still at roughly 85%, 90% versus the very, very first time at that same time interval, you would have decayed down to, you know, 50%, 40%.

    03:01 So, the take home message here is, repetition is key.

    03:04 So the more you access something, the more you activate a node, the more likely that you remember something.

    03:10 So, down to the MCAT.

    03:12 Don’t just read or memorize something once, revisit, revisit.

    03:16 Have study notes or re-read chapters, re-watches video over and over because it’s so amazing.

    03:22 And you’ll remember everything.

    03:23 So that comes time to the exam, you will ace this section.

    03:27 Okay. Now, interference from new learning may interfere with retrieval of older learning from memory.

    03:32 So this is a unique concept is that sometimes you learn new things.

    03:37 And whether it’s commonality or whether it’s a complete difference, it actually impacts older memories.

    03:45 So I’m trying to piece together an example here, but you may have learned, say, capitals of a country when you’re in grade school.

    03:53 And now, all of a sudden, you’ve taken up geography again and you’re learning all this new stuff around maps and you’re learning a whole bunch of new things around different cities and countries.

    04:05 That may actually impact some of the older stuff that you’ve learned and you’re going to have to either revisit the old stuff to reintegrate that with the new stuff.

    04:13 Or you’re going to end up decay and losing the old stuff and just have the new stuff.

    04:17 Okay? So proactive interference happens when previous information interferes with the ability to recall new information.

    04:23 So, let’s take a look an example where you park your car.

    04:26 So, you park your car in the exact same spot -- sorry, in exact same garage every day, but it’s a different spot every day.

    04:34 So, on Monday, you park in spot B, but then on Tuesday, Wednesday, Thursday, let’s say, Friday, you are like, “Geez, where did I park again?” because on Monday it was at A, then I parked at B on Tuesday, Wednesday was here, Thursday is there.

    04:51 And you now mix up where you parked today.

    04:55 So, you have difficulty in either recalling where you parked and where you parked your today because there’s all this information that’s interfering with one another.

    05:03 So we call that proactive interference.

    05:06 Retroactive interference happens when the newly learned information interferes with the ability to recall older information.

    05:11 So, do you remember your old phone number and you have your new phone number? Your new phone number is interfering with what your old number was.

    05:22 So, you know, if I ask you right now, “Can you remember your very first phone number as a child compared to what you have today?” Your new mobile cellphone number is probably interfering and blocking all the old numbers that you have.

    05:35 You might be able to remember like the one before the one you had now, but do you remember phone number that you had 10 times ago? Probably not.

    05:44 Positive transfer is when older info facilitates the learning of new information.

    05:49 So this is really good.

    05:49 This is building on your previous learning.

    05:51 That’s a good thing.

    05:52 So learning a related language.

    05:54 So, if you know something already like English and you’re trying to learn, you know, Latin, there’s a lot of words that, you know, the original underlying definition of an English word comes from Latin.

    06:07 So when you’re trying to learn Latin because you understand English, it’s a lot easier.

    06:11 Okay? So that helps a lot.

    06:12 Or say for example, if you play American football, there’s basic rules that you’ve learned, how to throw the ball, how to hold the ball, the basic rules.

    06:20 And then rugby, which is a different thing, has a lot of similarities.

    06:24 And so some of that learnings that you had from American football will translate into rugby which makes acquisition rugby a lot easier.

    06:32 Which is why after you’ve learned a couple of core languages, for example, it’s easier to stock on another that slightly somewhat related because you’ve already learned a lot of the basic rules and how that encoded and stored.


    About the Lecture

    The lecture Forgetting: Decay and Interference – Memory (PSY) by Tarry Ahuja, PhD is from the course Making Sense of the Environment.


    Included Quiz Questions

    1. Interference
    2. Memory decay
    3. Association between nodes
    4. Decay curve
    5. Long-term memory
    1. Positive transference
    2. Retroactive interference
    3. Proactive transference
    4. Neural network
    5. Interdependent network
    1. Proactive interference
    2. Retroactive interference
    3. Repetition interval
    4. Transference
    5. Failure in memory retrieval
    1. First few days
    2. First month
    3. First few months
    4. First year
    5. Years later
    1. Retention interval
    2. Recall interval
    3. Interference
    4. Forgetting curve
    5. Memory decay

    Author of lecture Forgetting: Decay and Interference – Memory (PSY)

     Tarry Ahuja, PhD

    Tarry Ahuja, PhD


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