Proactive and Retroactive Interference: Definition and Examples

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The term interference is used to explain why people forget long-term memories. There are two forms of interference: proactive interference, in which old memories disrupt the retrieval of new memories, and retroactive interference, in which new memories disrupt the retrieval and maintenance of old memories.

Key Takeaways: Proactive and Retroactive Interference

  • Interference theory is one of several theories that explain why we forget. It posits that memories compete, which means one memory may interfere with another when an individual is trying to retrieve information from long-term memory.
  • There are two kinds of interference: proactive, where old memories interfere with the recall of new memories, and retroactive memories, where new memories interfere with the recall of old memories.
  • While there is a great deal of evidence for interference, many of the studies that support the theory are conducted using memory tasks that are performed a short time apart. This reduces the studies’ ecological validity and ability to be generalized to real life.

Interference Theory

Psychologists are interested in what makes us forget just as much as they are in what makes us remember. Several theories explaining why we forget have been proposed. One is interference, which suggests that an individual may fail to retrieve information from long-term memory because other information interferes. Different pieces of information in long-term memory compete, especially if that information is similar. This leads to certain information being either difficult to recall or completely forgotten.

There are many instances where you might confuse one memory with another. For example, if you go to the movies on a regular basis, you may have trouble remembering who you went to a given film with. Each time you go to the movie theater, the experience is similar. Therefore, different memories of going to the movie theater may become confused in your mind because they are so much alike.

Studies on interference date back over 100 years. One of the first was conducted by John A. Bergstrom in the 1890s. Participants sorted cards into two piles, but when the location of the second pile was changed, participants performed more slowly. This suggested that after learning the initial rules of card sorting they interfered with learning the new rules.

In the 1950s, Brenton J. Underwood examined the Ebbinghaus forgetting curve, which plots out the brain’s inability to retain information over time. He proposed that previously learned information is just as much the reason for forgetting as time is. And because we are learning all the time, there are many opportunities between when we encode information in long-term memory and when we want to retrieve that information for new memories to form that may interfere with this process. 

Interference is divided into two types: proactive interference and retroactive interference.

Proactive Interference

Proactive interference happens when an individual is unable to learn new information because old information prevents its retrieval. In other words, old memories interfere with the retrieval of new memories. Older memories are often more strongly encoded in long-term memory because the individual has had more time to revisit and rehearse them. As a result, they are easier to recall than memories that were made more recently. Research has shown that one way to reduce proactive interference is to rehearse the new information through testing or recitation.

Proactive Interference Examples

We encounter numerous examples of proactive interference in our daily lives, including:

  • During the first month or two of every year, you may find yourself putting the previous year down whenever you write the date. This is because you’ve frequently rehearsed the previous year and it’s easier to recall than the new year.
  • Similarly, if you are trying to learn the Italian language but you previously learned Spanish, you may find yourself frequently recalling Spanish words instead of Italian words.
  • If you need to use a foreign currency while traveling to another country, you may have trouble mastering which bills and coins are for which denominations because your knowledge of the currency of your own country interferes with your ability to remember.

Retroactive Interference

Retroactive interference happens when an individual is unable to recall old information because new information prevents its retrieval. In other words, new memories interfere with the retrieval of old memories.

Retroactive interference has been shown to disrupt learning. In one study, participants learned a set of German-Japanese word pairs and then a different set as an interference task. The interference task was presented 0, 3, 6, or 9 minutes after the learning task. The interference task reduced learning by as much as 20% regardless of how long participants waited between being presented with the learning task and with the interference task. The researchers suggested that interference may disrupt memory consolidation.

Retroactive Interference Examples

Just like proactive interference, many cases where retroactive interference occur in our daily lives. For example:

  • If you’re an actor and must learn a new monologue for a play, you may forget the previous monologue you learned for a different play.
  • Likewise, suppose you’re a communication major in college. You learn a lot of theories of communication, but as you learn new theories you have trouble recalling the ones you'd learned previously.
  • After changing jobs, you learn the names of all your new co-workers. Then one day, you run into one of your co-workers from your previous job and incorrectly address them with the name of one of your new colleagues.


There is a great deal of research backing up the effects of proactive and retroactive interference. However, there are some issues with the theory. Most studies on interference theory take place in a lab using word memory tasks that are presented fairly close together. In real life, people rarely perform word memory tasks, much less with only a little bit of time between them. As a result, many of the studies of proactive and retroactive interference may not be generalizable to the real world.


  • McLeod, Saul. Proactive and Retroactive Interference.” Simply Psychology, 2018.
  • Nguyan, Khuyen and Mark A. McDaniel. "Potent Techniques to Improve Learning from Text." Applying Science of Learning in Education: Infusing Psychological Science into the Curriculum, edited by Victor A. Benassi, Catherine E. Overson, and Christopher M. Hakala. American Psychological Association, 2014, pp. 104-117.
  • Sosic-Vasic, Zrinka, Katrin Hille, Julia Kroner, Manfred Spitzer, and Jurgen Kornmeier. "When Learning Disturbs Memory — Temporal Profile of Retroactive Interference of Learning on Memory Formation." Frontiers in Psychology, vol. 9, no. 82, 2018.
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Vinney, Cynthia. "Proactive and Retroactive Interference: Definition and Examples." ThoughtCo, Aug. 29, 2020, Vinney, Cynthia. (2020, August 29). Proactive and Retroactive Interference: Definition and Examples. Retrieved from Vinney, Cynthia. "Proactive and Retroactive Interference: Definition and Examples." ThoughtCo. (accessed January 24, 2021).