Foraging Clues

Spring 2019


If you ever wonder why some people are willing to camp outside the Apple store overnight in  order to snag the latest iPhone, a team that includes a Johns Hopkins biomedical engineer found that the answer may lie in biological rules governing how animals typically forage for food and other rewards.

Their new study—in humans—affirms a theory known as optimal foraging, which holds that animals will adopt the most efficient foraging strategy possible so that they don’t expend more time and energy gathering food than they will get from the food itself. The study also added to evidence that the richer the reward, the faster people will move to get it. In other words, if buying that latest tech gizmo really matters to you, you’ll not only be willing to spend more, but you may also rush to be first in line to slap your credit card on the counter.

A description of the study—which tracked the speed and direction of eye movements among people as they looked at images on a computer screen—was published online in Proceedings of the National Academy of Sciences.

“Because animals that maximize optimal foraging live longer, in general, and are more ‘fit,’ traits that support such behavior are highly conserved in evolution and therefore are likely to inform human as well as other animal behavior,” says Reza Shadmehr, professor of biomedical engineering and neuroscience. “We believe that the speed at which an animal moves to the next reward, which we call ‘vigor,’ is related to this principle in people too.”

Shadmehr notes that understanding the principles of vigor may do far more than tell us about foraging for food or trendy gifts. It may also inform scientists about conditions that link human movement and cognition, such as Parkinson’s disease, a disease of the nervous system that affects movement and memory, and depression, which is characterized by slower movement as well as sadness and other mood problems.

Shadmehr also suggests that understanding vigor could advance understanding of economic theory, essentially how we make value choices. “The way we identify preference and choice could be measured in part by measuring innate vigor,” he says.