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Collaborative Inhibition: The Surprising Effect of Recalling Information in Groups

This post was originally published on January 10, 2020 on Psychology in Action.

The popular saying, “Two heads are better than one” suggests that it is better to collaborate with another person than to work alone. This idea has been supported by memory research, which has found that groups of people do indeed recall more than an individual (e.g., Yuker, 1955). Many would argue that it does not seem fair to compare two (or three or four) people against one—it seems only natural that groups would win out. To take an analogy from the world of sports, visualize if, in a game between your favorite team and their bitter rival, the referee allowed your opponent an extra three players on the field. You would be pretty upset. So, researchers decided to compare the memory of actual groups with what they termed nominal groups. Nominal groups are groups in name only, meaning that they worked individually, but afterward their responses were summed to create an artificial group. Imagine if participants in a psychology study were asked to memorize the following list of words:











Participants A, B, C, and D worked together as a group to recall as many words as they could. Group ABCD ultimately remembered six out of ten words: STOVE, LAMP, POTATO, FLOWER, SHELF, and HOUSE.

Participants E, F, G, and H each recalled separately.

  • Participant E remembered HOUSE, TREE, and LAMP

  • Participant F remembered SHELF, APPLE, and TREE

  • Participant G remembered FLOWER, TABLE, and CAR

  • Participant H remembered SHELF, FLOWER, and LAMP

Participants E, F, G, and H were then combined into Nominal Group EFGH. Nominal Group EFGH ended up recalling eight out of ten words: HOUSE, TREE, LAMP, SHELF, APPLE, FLOWER, TABLE, and CAR. For nominal groups, only nonredundant responses are counted: Even though Participant E and Participant F both remembered TREE, it is only counted once for Nominal Group EFGH.

Nominal groups represent the idealized potential of a specific group of people. Though working alone Participants E, F, G, and H did not remember as much as Group ABCD, they did remember more total information when their responses were summed, despite no apparent explanation for why they would perform better.

This example highlights the fascinating phenomenon known as collaborative inhibition (Weldon & Bellinger, 1997). Comparing actual groups to nominal groups reveals that actual groups consistently recall less information than nominal groups. In other words, actual groups tend to underperform compared to their group’s potential.

What might be the cause of collaborative inhibition? The leading hypothesis is that it is due to retrieval disruption that occurs during group recall (Basden, Basden, Bryner, & Thomas, 1997). When asked to remember something, each person chooses a way to organize the storage and recall of that information in a way that they think is easiest, resulting in different people using various memory strategies. This is illustrated by the following example:

Imagine that Participants S, T, U, and V are asked to memorize the following list of words.













Before reading on, how would you try to remember these words? Take a moment and think about how you might organize these words to help you remember them later.

Now, let’s imagine each participant chooses a different retrieval strategy.

  • Participant S decides to organize the list by color of item: blue, orange, and red.

  • Participant T decides to organize the list by type of item: foods, animals, and inorganic objects.

  • Participant U decides to tell a story with the words: “One time a TIGER was eating a big hamburger with lots of KETCHUP and it spilled all over him! He decided to take a swim in the OCEAN under the bright blue SKY to clean up…”

  • Participant V decides to memorize the words in alphabetical order: BLUEBERRY, KETCHUP, KOI, LAVA, MANGO, etc.

When recalling individually, the fact that each participant chose a different retrieval strategy isn’t a problem—each person can recall the words in whichever order they please. However, as a group, things start to get difficult. Participant S begins listing blue words (i.e. OCEAN) and then Participant U jumps in with TIGER and KETCHUP, throwing off Participant S. Participant T follows up KETCHUP with other food words like BLUEBERRY and MANGO causing Participant U to lose track of their carefully crafted story. None of the words are remotely in alphabetical order, and this reduces Participant V’s ability to remember the missing item between BLUBERRY and MANGO.

Clearly, it can become a bit of a mess.

Though collaborative inhibition has been shown for many different types of materials, it does not always occur. Conditions that increase the likelihood that people’s retrieval strategies align tend to reduce, or completely eliminate, collaborative inhibition. Collaborative inhibition tends to occur in free recall when participants are asked to simply remember all that they can but is not present during cued recall (i.e. What is the capital of the United States?) or recognition memory tasks (i.e. Did you previously see the word “carpet”?) because it is likely that the way people try to remember that information is highly similar. Likewise, lists that have smaller categories (i.e. seasons of the year) as opposed to larger categories (i.e. months of the year) tend to show little or no collaborative inhibition because the categories are more tightly organized (Rajaram & Pereira-Pasarin, 2011).

To conclude, though it may contradict people’s intuitions about groups and memory performance, the results from psychological research are undeniable: Despite popular belief, two heads are not always better than one.


  1. Basden, B. H., Basden, D. R., Bryner, S., & Thomas III, R. L. (1997). A comparison of group and individual remembering: Does collaboration disrupt retrieval strategies? Journal of Experimental Psychology: Learning, Memory, and Cognition, 23, 1176–1189.

  2. Rajaram, S., & Pereira-Pasarin, L. P. (2010). Collaborative memory: Cognitive research and theory. Perspectives on Psychological Science, 5(6), 649-663.

  3. Weldon, M. S., & Bellinger, K. D. (1997). Collective memory: Collaborative and individual processes in remembering. Journal of Experimental Psychology: Learning, Memory, and Cognition, 23, 1160–1175.

  4. Yuker, H. E. (1955). Group atmosphere and memory. Journal of Abnormal and Social Psychology, 51, 117–123.

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