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Interference is one theory to explain how andwhy forgetting occursin long-term memory. Interference is a memory phenomenon in which some memories interfere with the retrieval of other memories.
Here we explore interference in greater detail, including how this theory developed and how it was expanded on with decay theory. We also discuss the two types of interference in psychology: proactive interference and retroactive interference, along with providing examples of each.
What Interference Is
Essentially, interference occurs when some information makes it difficult to recall similar material. Similar memories compete, causing some to be more difficult to remember or even forgotten entirely. Because of this, some long-term memories cannot be retrieved intoshort-term memory.
With interference, one might confuse the memory of one event with another. This experience can be surprisingly common, especially when faced with a number of very similar memories. If someone is asked to recall what they had for breakfast last Monday, for example, they might struggle to remember because they have so many similar memories of other meals.
There are many different but similar memories encoded in long-term memory, which can make it challenging to recall a specific event and bring it into short-term memory.
History of Interference Theory
Researchers have long been interested in understanding not onlyhow memory worksbut why people sometimes forget. Interference theory is just one of several proposed explanations, with some important studies contributing to the development of this theory.
In one of the first studies on interference, researcher John A. Bergstrom had participants sort cards into two piles. He found that changing the location of the second pile resulted in slower performance, suggesting that learning the rules for the first task interfered with the memory of rules for the second task.
In 1900, researchers Muller and Pilzecker found that people were less likely to recall nonsense syllables if intervening material was presented 10 minutes or sooner following the original learning task. To them, this indicated that new memories require a period of time to stabilize in memory, a process they dubbed “consolidation.”
What Is Memory Consolidation?
Decay Theory
Decay theory elaborates upon Ebbinghaus’s research and suggests that memories decay over time, leading to forgetting. However, a memory may also be susceptible to a number of other influences that affect how well things are recalled and why they are sometimes forgotten.
Many events can take place between the time a memory is encoded and when it is recalled. How rarely (if ever) do we form a memory and then learn nothing new between the formation of that memory and the need to recall that information? Such conditions usually only take place artificially in experimental labs.
While researchers can control for other factors in a lab setting, the real world is filled with a variety of events that may also have an impact memory.
In day-to-day life, any number of events, experiences, andnew learningcan occur between the actual formation of one memory and the need to recall that memory. When intervening gaps between encoding and recall are filled with other information, there is a corresponding negative impact on memory.
Due to this phenomenon, it can be challenging to determine if forgetting is because of the passing of time or if it is a consequence of one of these intervening factors. Research suggests, for example, that interfering memories are one factor that can also contribute to forgetting.
Two Types of Interference
There are two different types of interference: proactive interference and retroactive interference.
Proactive InterferenceWhen an old memory makes it more difficult or impossible to remember a new memory.Retroactive InterferenceWhen new information interferes with the ability to remember previously learned information.
Proactive InterferenceWhen an old memory makes it more difficult or impossible to remember a new memory.
When an old memory makes it more difficult or impossible to remember a new memory.
Retroactive InterferenceWhen new information interferes with the ability to remember previously learned information.
When new information interferes with the ability to remember previously learned information.
Proactive Interference
Proactive interference is when older memories interfere with the retrieval of newer memories. Because older memories are often better rehearsed and more strongly cemented inlong-term memory, it is often easier to recall previously learned information rather than more recent learning.
Proactive interference can sometimes make it more difficult to learn new things.For example, upon moving into a new house, one might find themselves accidentally writing their old address down when filling out forms. The older memory of the previous address makes it more difficult to recall the new one.
Retroactive Interference
Retroactive interference is when newer memories interfere with the retrieval of older memories. Essentially, this type of interference creates a backward effect, making it more difficult to recall things that have been previously learned.
In the case of retroactive interference, learning new things can make it more difficult to recall things that we already know. For example, a musician might learn a new piece, only to find that the new song makes it more difficult to recall an older, previously learned piece.
Research has found that around 70% of information is forgotten within 24 hours of initial learning.
While retroactive interference can have a dramatic impact on theretention of new knowledge, there are some effective strategies that can be implemented to minimize these effects. Overlearning is one effective approach that can be used to reduce retroactive interference, which involves rehearsing new material past the point of acquisition.
Overlearning means studying and practicing what we have learned over and over, even after we’ve achieved sufficient mastery of the subject or skill. This practice helps to ensure that the information will be more stable in long-term memory and improve recollection and performance.
Examples of Interference
There are many different examples of how interference can influence everyday life. Imagine a studentpreparing for a psychology exam. Between learning the information and taking the actual test, many things can take place. The student may take other classes, work, watch television, read books, engage in conversations, and perform many other activities during this intervening period.
If they’ve learned subsequent material that is very similar to the original information, recalling facts and details for the exam might be harder. They might find themself mixing up differenthistorical figures in psychologyor struggling to remember theorigins of this field.
The memories formed during the interval between the learning and the test interfere with the older memories, making recall much more difficult.
There are many other examples of interference and its effect on our memories:
Interference Research
For example, participants may be presented with the original information and then after a period of time, presented with more information. When tested on what they recall, interference is observed more frequently when the secondary information contains more similarities to the original material.
The more similar two memories are, the more likely it is that interference will occur.
Earlier Research
In one of the earliest studies on the interference theory of forgetting, researchers had subjects memorize a list of two-syllable adjectives.Later, subjects were asked to memorize one of five different lists. Some of these lists were very similar to the original test material, while others were very different.
For example, some lists contained synonyms of the original words, some antonyms, and some were simply nonsense syllables. Later testing showed that recall improved as the differences between the two lists increased. The more similar the lists were, the more interference there was, leading to moredifficulty with recall.
Later Research
In one 2018 study, researchers found that retroactive interference had a negative impact on learning and memory consolidation.After a learning task, some participants were presented with a subsequent interference task at various time points. Some had the second learning task three minutes after learning the first information, while others had it nine minutes after.
Interference can play a prominent role in the learning process. Previously learned material can have an impact on future learning and, conversely, newly learning information can affect past learning. One study found that retroactive interference effects were more profound in younger children, but that these effects may diminish as people age.
Applications of Interference Theory
Interference theory can have a number of real-world applications. From a practical, everyday standpoint, interference theory suggests that one of the best ways to improve one’s memory of something is to make it stand out.
If we are trying to remember something and want to avoid the effects of interference, we should look for a way to add novelty.Making up a mnemonic, song, or rhyme is one way to help make what we are studying stand out in our memory.
By making the material memorable and less similar to other memories, it may become easier to recall. Regular practice sessions can also be useful for promoting overlearning and reducing the probability that new memories will interfere with what we are learning now.
Summary
While interference is just one explanation for why we forget, it is an important one. The competition between similar memories might make it much more difficult to recall things we have learned in the past. This interference can also make it much more difficult to recall more recent memories, which can make learning difficult.
Studies in lab settings support the existence and impact of interference. But in real-world settings, it is much more difficult to ascertain just how much of forgetting can be linked to the effects of interference.
Different Types of Memories
9 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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