The human mind is like a book with an infinite amount of pages and more and more pages are added every single day because we are constantly bombarded with information left and right.

What we retain from this information is actually the memory we hold in our mind.

In order for us to even remember certain information we first need to come into contact with it, in other words we need to learn it and given the fact that, as I said, we collect new information every day what happens with the old memory of the things we already learned, and vice versa, is a question we today will try to answer.

We see that there is some kind of interference going on in our brain when we want to recall old memory because of the things we recently learned or on the other hand the things we learned recently could be mixed up with the things we knew before that.

And this is a common occurrence because we can’t help but try to use all of our information stored in our brain in order to give an answer to the tasks, struggles, and obligations of our day-to-day life.

The idea is that this interference occurs because our long-term and short-term memories interfere with and disrupt each other meaning we forget things because both of those memories are used when we try to recall certain information.

There are two types of interference:

  1. Proactive interference – old memories disrupt new ones.
  2. Retroactive interference – new memories disrupt old ones.


As I said, proactive interference occurs when the memories we already know restrain our capacity to recall the information we only recently learned which leads to us not being able to remember and understand that information.

And this is so common that everyone has had an experience with proactive interference especially when we are trying to comprehend similar subjects such as learning a new language or trying to remember two lists of groceries to buy.

Also, there is a connection between forgetting working memories and proactive interference because we couldn’t forget our working memory if it wasn’t for proactive interference meaning that we would easily be able to distinguish between old and new memory without any interference.

But we know that this isn’t the case because our working memory serves one purpose and that is a quick and immediate conceptual and linguistic processing.

It’s just short-term memory we use right then and there without much thinking because if we were to think of it too much we wouldn’t be as effective when using it.

So our brain does a fairly great job in filtering the information we don’t need, using the information we need right now, and storing information that we will need later.

Where does that leave proactive interference you may ask?

As it turns out we can’t remember exactly when we learned old and new information, for example, you learned some things at school which you use every day like calculating, reading, writing and so on, but you can’t remember the exact day, hour and minute you’ve learned those things.

If you can, congratulations, you have an awesome memory.

For most of us, that isn’t relevant information we need to know in order to use the information we learned at school and we just look at the memories in our brain as a whole instead of time-specific data.

In other words, our brain doesn’t care if it is old or new memory we need to use, it is using both memories in order to solve a specific problem.

This means that proactive interference is sometimes unavoidable.


I’m going to list some of the most common examples of this occurrence I’m sure all of us will recognize and in one point or another in our lives have experienced:

  1. Every New Year, after the first of January most people catch themselves to write the previous year when writing dates. This is particularly common with students when they come back from winter holidays and they start to write a new lesson or even while taking a test.
  2. This second example is specifically meant for women who once they get married and change their last name sometimes tend to say their previous last name without thinking about it.
  3.  When you start learning a new language, for example, Italian, but you’ve learned Spanish before that, what you may experience is that you could end up mixing the vocabulary or grammar of the two languages simply because you’re already used to how the first language is spoken.
  4. Also, a common example is when we get a new phone number and then when someone asks us for the number we may fall into the trap of giving them our old one because we are just getting used to the new phone number.
  5. The last example I want to make is when we read a book we already read before and then all of a sudden it feels as we are reading a completely different book because we either didn’t remember the whole story or the things we do remember about it just vaguely slip our mind so now it seems as we are filling the gaps of the version we created in our minds when we first read the book.

There are a number of specific examples we could add but these are some of the more common ones which I’m sure you will pay attention to from now one once you’ve learned about them.


In contrast to proactive interference, retroactive interference is the occurrence when new information gets in the way of our old memories meaning we get a disrupted image of the things we already know by learning or implementing new things.

As in proactive interference, this is also a very common situation to be in and a lot of things depend on its occurrence, for example if you are perhaps a martial artist trying to learn new moves, you will find it hard to recall the old physical moves because the new moves you’ve learned are much fresher in memory and were more recently practiced.

To get back to the point I made when talking about proactive interference, in retroactive interference, there seems to be an issue of unlearning the things you’ve known before by overwriting them with new information.

This could be a huge problem considering the fact that if you rewrite old memory using new memory, there is no guarantee that this new memory will be more useful or even will you be able to recall to it better in the future.

What I’m trying to say is that if we don’t catch ourselves not being able to recall our old memory which is disrupted by new information, we could fall into the trap of doing a disfavor to our brain by in some way suppressing old information and exchanging it with a new one.

I could imagine this being a good thing when for example you hated math and everything you know about math seems to you like torture but suddenly you’ve learned something from your friend who is a mathematician or you’ve watched an informative video about math so now you realize that math isn’t that bad just that what you’ve learned now is more effective and useful than what you’ve learned from learning it for 8 years in school.

I mean the same goes for any other subject you’ve hated in school, so in reality, retroactive interference is a double-edged sword depending on how you view it.


Just as with proactive interference, the retroactive interference we experience from time-to-time is a common circumstance so let’s list a few more frequent examples:

  1. One of the most common examples of retroactive interference is when a student remembers better what he learned at the end of the school year in comparison to the beginning of the school year.
  2. Another common example is when you start learning a new language, for instance, German, and let us say you’ve learned French before that, now when you try to speak French, the new words you’ve learned in German will start to pop-up interfering with your knowledge of French.
  3. When you learn new dance moves and later try to dance like you used to before, you may experience that you’re unable to do so because the new dance moves you’ve learned now somehow seem to be in the way of the old ones so you mix them up.
  4. Just as in the example for proactive interference, when you get a new phone number, you might not be able to remember your old one because you’re not using it anymore and you don’t have any use of knowing it.

As you see these situations have surely happened to you once or twice and maybe not at all but it’s important to know which situations can trigger retroactive interference so you can try to avoid making mistakes in the future.


Although they cause the opposite effect of one another, both proactive and retroactive interferences do have some similarities which can be observed in their common occurrence.

  1. They are both based on the Interference theory, which suggests that the interference must result in either one way or the other.
  2. They rely on context in order for the interference to actually occur meaning they can both be triggered by the same situation, for instance when learning a new language or getting a new phone number as we mentioned before.
  3. The competition and association of old and new memories are what causes the disruption of memory in both of these interferences.

These similarities mean that they have the same root just not the same consequence and it all depends on the situation that we’re in and also on our perception in that given moment.


We’ve explained the main difference between these two interferences in terms that the first one disrupts new memories with old ones and the other disrupts old memories with new ones, but now we should explain how exactly do both interferences affect our mind and memory.

  1. Competition and unlearning The competition between old and new memories is what causes both interferences but in the case of retroactive interference the process of unlearning is also an important occurrence.
  2. Forgetting In terms of proactive interference, not being able to retain new information and quickly forgetting our working memory sounds bad and it is, while for instance when we talk about retroactive interference it lets us forget the information we don’t need at that given time and replaces it with new information.
  3. Rest time It is strange how rest time doesn’t seem to have any effect on proactive interference but in the case of retroactive interference it does have a significant impact on a person’s ability to block it out.

We see that these differences have a great impact on the overall consequences of the interferences and do shed some light on why in some situations there is no rule whether we will experience one or the other interference.


Even though we explained what proactive and retroactive interference is, there are some shortcomings which should be examined in order for us to understand whether this is a common phenomenon related to all the information we receive or is there more to it.

What the critics of the Interference theory have to say is that its main weakness comes from the lack of evidence that this interference could occur in all the information we retain and that just the information in a similar format causes the interference.

This means that the interference is more likely to occur in situations when the old memory and the new memory compete with each other based on a related subject.

To make a perfect example of these claims I will use the examples I already gave for both the proactive and retroactive interference and that is learning a new language which either disrupts the language they already learned or the previous language disrupts the use of this new one.

We clearly see that both interferences can occur in the same situation and that is learning a new language, but this is only if we learned a language before that and for instance our native language would not be disrupted in one way or another mainly because we already use it constantly and don’t have to recall it at all.

The same goes for the other examples I’ve given and this is quite strong evidence which backs up the skeptics of the theory, but there are also plenty of psychologists who suggest that the theory is still true.


Now that we’ve heard what the critics have to say, we should focus on the part of the theory which does have some chance of being true and is essentially based on the arguments which the critics use to abolish the theory.

The argument is that the interference occurs in situations with a similar format and by that the overall occurrence of the interference is confirmed and even agreed upon by both skeptics and non-skeptics of the theory.

The second argument for the theory is that it is such a common occurrence in every-day life that there is a great number of examples and even tests which have been carried out on the side of proving the plausibility of the theory.

Whether you believe the weaknesses or the strengths of the theory, the reality is that both proactive and retroactive interferences are occurring when we don’t even think about it or not.

Truth be told, this theory has been researched for a little less than some sixty years so there are more questions to be opened and answered on this topic but that doesn’t mean it’s a false theory just that it needs further research done.

I’m sure that in the future there will be more psychologists interested in this field of psychology and these kinds of articles help to shed some light on such topics.


It seems that there is one memory that the proactive and retroactive interference can’t disrupt and that is odor memory.

Believe it or not, our ability to memorize certain smells and fragrance is so powerful that we can without any problems recall if we’ve already smelled that scent before or not.

Psychologists believe that we’ve developed this ability to memorize certain scents back when we were cavemen in order to detect danger by knowing which plants are poisonous or not to know to eat them and also by knowing the scent of the pheromones of animals that are in our near presence.

Also, our ability to smell is directly connected to our ability to taste food which means that we also can’t mix-up similar tastes of food leading to a conclusion that there still are some weaknesses to the interference theory which should be further put to the test.

It’s amazing how this ability survived the test of time and how it can now be applied to the study of interference theory but most importantly how it can help us to understand the memory of the human mind which as it shows is more based on experience than on abstract thoughts.

All in all, this is an interesting point to make when talking about the interference theory, whether it serves as an argument for those who are opposed to it or not is a matter of psychological studies which should be kept in the laboratories for now.


The main goal of understanding the cause of these interferences should be to know how to stop them from occurring or at least minimizing their effect because they can put you in awkward situations you don’t want to be in.

Let’s take for example learning a new language and then not being able to use it properly because you’re bombarded with the grammar of the language you’ve learned previously.

A quick fix to this problem is to try to recall both translations in your native language so that way you will select the translation you need.

How do you think linguists and polyglots function?

Because they’ve mastered the languages they speak to such extent that they know a whole vocabulary of words and their brain is wired that way not to mix them up, so you can learn a thing or two from them and the things we talked about today in order to resolve this problem.

Another point I want to make is that, although these interferences are a common occurrence they are not the cause of memory loss just the process of forgetting the information you don’t need which isn’t that bad.

Once you understand what they are and what causes them you will be one step ahead of knowing how to avoid the interferences from happening.


In conclusion, I would like to summarize everything we’ve talked about today by saying that these interferences are normal and don’t need to bother you too much if you experience them from time-to-time but also that by understanding them you will be more likely to spot if the interference is to come up.

And although they can sometimes be embarrassing such as the situation when a woman mistakenly says her previous last name, they are a good mechanism for knowing how our brain works and reacts to similar content and to information we don’t even think about.

There isn’t really any evidence that these interferences are a sign of memory loss or some neurotic disorders rather that they are proof that your brain is working it’s best to use all the memory and knowledge it has.

So if you think of it that way, if you’re experiencing proactive and retroactive interference it means that you’re using your brain to its full capacity, we’re not machines so a mix-up here and it is acceptable.

Proactive and Retroactive Interference Explained

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