Quick, name all the animals that you can think of – you’ve got three minutes. Dog, cat, rabbit, hamster, goldfish … ?
If you falter after naming a group of common domestic pets, you may have exploited a specific memory patch and need to move on to forage elsewhere for new words. That’s the basic finding behind research by Thomas Hills, a former research scientist at IU Bloomington now at the University of Warwick, along with Michael N. Jones, assistant professor of psychological and brain sciences, and Peter Todd, professor of cognitive science, at IU Bloomington.
Just as animals forage for food–birds flying among berry bushes or bees flitting between flowers–people forage for memories, say the researchers in “Optimal Foraging in Semantic Memory,” a study published in Psychological Review earlier this year.
Once an animal has exploited the resources of a particular bush or tree or flower, it will move on, switching from searching a local patch to a global search for other patches. We do the same thing when we’re searching for memories. Asked to name animals, for instance, we first focus on specific clusters of information such as domestic pet types. But when we run out of pet animal names, we move on to a new patch, say, zoo animals or sea creatures.
Hills and his colleagues asked 141 undergraduate students at IU Bloomington to name as many items as possible from various categories (animals, food, vehicles, occupations, sports, cities, and movie titles) within a three-minute time frame. The researchers determined that memory search functions very similarly to searching in physical space. Participants switched from “patch” to “patch” in the same manner that optimal foraging theories predict that animals shift their searches for food.
Our memory searches, the co-authors write, involve “a dynamic process of mediating between local exploitation and global exploration of clusters of information in much the same way that animals forage among patches of food in their environment.”