Doug Bonderud

Dec 28th 2020

How Does the Brain Work? Study Suggests Search Engine Similarity


How does the brain work? While our bone-covered meat minds are a remarkable feat of evolutionary adaptation, they remain functionally obscure. And despite a thorough debunking of the 10% myth (sorry, there’s no telekinesis or titan-level super strength on the horizon), we’re still searching for the source of specific human traits, such as creativity, and remain uncertain about what, why and how humans remember.

However, thanks to a recent NIH study, scientists are getting closer to unlocking the mystery of memory by mapping memorable words — and as it turns out, we’re not so different from your favorite search engine.

Solving for SEO

Why are some words more memorable? Why do specific phrases jump more easily to mind while others are a struggle to recall?

Common wisdom suggests that two key factors underpin the process of how to memorize words: frequency of use and concreteness. It makes sense, since the more often you see or use a word in everyday life, the more likely you should be able to recall it on demand. And the more “concrete” a word — the more easily it maps to a simple concept — the quicker your brain should call it up. Compare the word “door” to the word “portal.” The first has a familiar, concrete definition while the second is more nebulous.

However, it’s not quite so straightforward. According to NIH study lead Dr. Weizhen Xie, a cognitive psychologist and post-doctoral fellow at NIH’s National Institute of Neurological Disorders and Stroke (NINDS), his team discovered that “some words are much more memorable than others.” According to Xie, “Our results support the idea that our memories are wired into neural networks and that our brains search for these memories, just the way search engines track down information on the Internet.”

Semantically Speaking

Dr. Xie’s research started by re-analyzing the results of a word-pair test conducted with patients who suffer from intractable epilepsy — seizures that can’t be controlled with medication. Participants were shown word pairs, such as “hand” and “apple” from a list of 300 nouns, then shown one of the words individually and asked to recall its pair. The results showed that the five top-recall words were seven times more likely to be remembered than the bottom five, no matter how the pairs were organized. Xie’s team was initially skeptical, given the impact of epilepsy on key brain functioning and connections, but a slew of similar results from a broader sample of more than 2,600 online participants yielded the same outcome.

So, how does the brain work when it comes to memorizing words? The study suggests that semantics play a critical role. When words are semantically similar — more closely linked to the meanings of other words — our brains are more likely to remember them, creating a kind of search engine-like operation when we try to recall words. Just like the “most relevant” answers that appear when you start typing your query, the human brain reaches for semantically similar words to provide context as quickly as possible.

This creates an interesting effect: Xie’s team found that situationally specific words such as “tank,” “doll” and “pond” were remembered more easily than more common words such as “street” or “cloud.”

For Better or Worse

Along with semantic similarity, research also suggests a monogamous memory component. According to a multi-university study, more memorable words have a single meaning and few synonyms, making them easier to recall than those with more “noise.”

Consider the word “light.” Two meanings spring to mind: one of weight and one of energy. Synonyms also abound, from “bright” and “glowing” to “airy” or “thin.” This creates a host of mental connections but could cause specific words to get lost in the shuffle. Compare this with a word like “pineapple.” It has one meaning — the spiny, tropical fruit — and in English, it has no synonyms, making it entirely monogamous and effectively more memorable.

Improving the Mental Model

When Xie and his team wrote a new computer model that used semantic connection as the basis for determining how to memorize words, it aligned with participant results. Meanwhile, those based on frequency of use or concreteness missed the mark. This suggests that our brains leverage specific language encoding and recall processes — and that more information about how this process works could help better map human memory.

“Our memories play a fundamental role in who we are and how our brains work,” says Xie. “However, one of the biggest challenges of studying memory is that people often remember the same things in different ways, making it difficult for researchers to compare people’s performances on memory tests.” But if scientists can uncover common rules — such as the use of semantic connections and monogamous meanings to prioritize recall — it may be possible to create a unified theory of intelligent operations and develop a shared memory model that better describes humans’ overall mental health.