The human brain is arguably the most powerful machine in the known universe, its inner workings an profound, impenetrable mystery. Except when it comes to remembering things. In that case, it's basically the same thing as a bird finding dinner.
This isn't the most flattering description of the human brain ever devised — actually, I might give that honor to "the most powerful machine in the known universe" — but it's actually useful in understanding how memory works. According to a team of researchers from the University of Warwick and Indiana University, the way that we search through our memories involves much the same strategies as a bird searching through bushes for berries.
That berry- and possibly memory-finding strategy is described by what's known as the Marginal Value Theorem, which describes when an individual, no matter the species, will abandon one nearly depleted resource in favor of another. Warwick psychology professor Dr. Thomas Hills explains:
"A bird's food tends to be clumped together in a specific patch – for example on a bush laden with berries. But when the berries on a bush are depleted to the point where the bird's energy is best focused on another more fruitful bush, it will move on. This kind of behaviour is predicted by the marginal value theorem, for a wide variety of animals.
The researchers tested whether this theorem could also explain the workings of human memory. To that end, they asked research participants to name as many animals as they possibly could in three minutes. The ways in which the participants tended to cluster different types of responses together pointed to different "patches" in memory containing different categories of animals. The humans moved through these memory patches just like a bird in the bushes:
"When faced with a memory task, we focus on specific clusters of information and jump between them like a bird between bushes. For example, when hunting for animals in memory, most people start with a patch of household pets — like dog, cat and hamster. But then as this patch becomes depleted, they look elsewhere. They might then alight on another semantically distinct ‘patch', for example predatory animals such as lion, tiger and jaguar."
Obviously, there's lots of different ways to access memories, but what this research points to is potentially the optimal way to recall a long list of related items. Of the 141 undergraduates who participated in the study, the ones who recalled the most animals were the ones who opted to switch between patches just as the marginal value theorem would have dictated. Yes, it seems that the term "bird-brained" has just taken on a horrifyingly literal new meaning.