The Grass is Always Greener…Or is It? The Neural Basis of Searching Behaviors

What motivates some to constantly seek out the next best thing, the greener grass, while others of us are content to stick with what’s known and safe? Our ancient ancestors had to forage in the savanna for food and water, but there was no telling where they would find these resources. The environment was patchy and unpredictable. So what was the best search strategy? Once you find a hunting ground with some antelope in it, do you set up camp and make it your own, or go looking for a better hunting ground, then a better one still?

Psychologists are very interested in this question, and some believe it may reflect a fundamental difference in cognitive style, wired into our neurons. Our challenges are perhaps more intellectual and abstract, but we still have to decide how to deal with an uncertain world. Faced with a problem or decision or choice, do we bear down and exploit one idea for all it’s worth, or move rapidly on from one solution to another to another? Or maybe we do both, depending on the problem, toggling back and forth depending on what works.

Indiana University psychologists Thomas Hills, Peter Todd and Robert Goldstone wanted to see if people do indeed have a consistent cognitive style for foraging, whether it’s for food or ideas. They also wanted to see if priming those ancient foraging mechanisms influences the way people approach modern problems.

The researchers used some modern tools: a computer game and a board game. They had a group of volunteers use icons to “forage” in a computerized world, moving around until they stumbled upon a hidden supply of resources (akin to food or water), then deciding if and when to move on, continue the search, and in which direction, and so forth. The scientists tracked their movements.

But the volunteers explored two very different worlds: Some foraged in a “clumpy” world, which had fewer but richer supplies of nutrients. Others explored a “diffuse” environment, which had many more, but much smaller, supplies. The idea was to “prime” the optimal foraging strategy for each possible world. Those in a diffuse world would in theory do better giving up on any one spot quickly, and moving on rapidly, and navigating to avoid any duplication. Those in a clumpy world would be more likely to stay put, exploiting the rich lodes of resources rather than keeping up the search.

Next, the volunteers participated in a more abstract, intellectual search task: a version of the board game Scrabble. They received letters as if they were going to play, and had to search their memory for as many words as they could make with those letters. As with the board game, they could also choose to trade in all their letters for a new set whenever they wanted to.

The researchers compared the volunteers’ Scrabble strategies with their foraging strategies, to see if they stuck with the letters they were given—or rapidly abandoned one set of letters for another set where they could have renewed success.

As reported in the August issue of the journal Psychological Science, a journal of the Association for Psychological Science, those who searched for diffuse resources benefiting from exploration in the spatial foraging task were also more restless and exploratory in the Scrabble task, while those facing a clumpy spatial environment benefiting from exploitation were more focused and persevering when they switched to the abstract mental challenge. Put another way, the human brain appears capable of using exploration or exploitation depending on the demands of the task, but also has a tendency via “priming” to keep searching in a similar way even if the domain changes.

The psychologists also found that individuals were consistent in their cognitive style. That is, the most persevering foragers were also the most persevering Scrabble players.

These findings have serious implications related to other recent work on brain chemistry and cognitive disorders. Exploratory and inattentive foraging—actual or abstract—appears to be linked to decreases in the brain chemical dopamine. Similarly, many problems related to attention—including ADHD, drug addiction, some forms of autism and schizophrenia—have been linked to such a dopamine deficit. It’s possible, the psychologists say, that computer foraging might reveal underlying cognitive style—either persistence or exploration. It’s even possible that such simulated foraging could have long-term effects on thinking style, and could perhaps lead to therapies for such cognitive disorders.