Clustering for Memory and Recall

Child using clustering to memorize information
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Clustering involves organizing information in memory into related groups. Memories are naturally clustered into related groupings during recall from long-term memory. So it makes sense that when you are trying to memorize information, putting similar items into the same category can help make recall easier.

How Does the Clustering Process Work?

Have you ever tried memorizing a long list of words? Imagine that you are trying to remember lists of vocabulary words for a biology class. One way to make it easier to remember the items on your list is to break it down into smaller groups of related items. Instead of simply trying to remember the entire list in the rote form, you might cluster information into smaller groupings according to whether the items are related to topics such as cell division, genetics, ecology, or microbiology.

How to Use Clustering to Remember More

This strategy can be used effectively when trying to memorize long lists of information. For example, imagine that you are trying to memorize a long grocery list. One way of making the information more manageable would be to cluster items into related groups. For example, you might make separate clusters for vegetables, fruits, grains, meats, and dairy items.

Let's take a look at another example of clustering. Read the following list of words:

grapes table bus apple chair airplane desk banana sofa car train plum lamp motorcycle strawberry dresser bicycle peach

Chances are that you automatically grouped these items into three clusters: fruits, furniture, and modes of transportation. Consider how difficult it would be to try to memorize the above list of words in order of presentation. By reorganizing the information and connecting each item to related items, you would be much more likely to remember more.

Clustering Methods

How do you decide how to form the different clusters? While this may be obvious for some lists, it will be less so for others.

  • Hard Clustering: In the above example, something either is a fruit or isn't, so it's easy to make the distinction. In hard clustering, you separate the items by distinct qualities. Think about what makes the items in the list distinct. You may have some leftovers that don't seem to have qualities in common.
  • Hierarchical Clustering: Start with all of the objects in the group and begin to group them two by two for the ones that are the most similar. Then look at the pairs and group the closest pairs together so that you now have groups of four. For simple memorization, that's probably as far as you want to go.

Clustering Effects for Memory

Research into memory has found two common types of natural clustering.

  • Temporal Clustering: You are more likely to recall items that are in neighboring positions on lists. For example, if the bird is followed by toast, you are likely to remember toast after bird if you memorized the list in order.
  • Semantic Clustering: You are more likely to recall similar items from the list. This is the type of clustering you are maximizing by breaking a list into similar items and then memorizing them in clusters. Semantic clustering can be paired with temporal clustering in this way.

By Kendra Cherry
Kendra Cherry, MS, is an author and educational consultant focused on helping students learn about psychology.