Monday , January 18 2021

The richer the reward is, the faster you will probably move to reach it, study shows

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If you wonder how long you personally are willing to queue to buy the hot new vacation, researchers at Johns Hopkins Medicine say the answer to the biological rules that govern how animals typically taste food and other rewards.

They report that the results of a new study in humans confirm the theory known as "optimal foraging", which implies that the animals are established to maximize the rewards they acquire based on factors such as the value of the reward itself and the time and effort spent to reach that reward. They also add to evidence that the richer the reward is, the faster people will move to get it. In other words, if you buy the amazing gift really matters, you will not only spend more, you can rush to be first in line to nab it.

A description of the survey was published October 15th in Test of the National Academy of Sciences.

"Because animals maximizing optimal foraging live longer generally and are more" fit "features supporting such behavior are highly preserved in evolution and therefore likely to inform both human and other animal behaviors," says Reza Shadmehr, Ph .D., Professor of Biomedical Engineering at Johns Hopkins University School of Medicine. "We believe that the speed at which an animal moves to the next reward, which we call" power ", is related to this principle also in humans."

To study vigor in humans, Shadmehr and his colleagues traced the speed and direction of eye movements among 92 people (average age 27, 51 men and 41 women) when they watched images on a computer screen. Studying rapid eye movements between objects (movements known as "saccades") is a frequent model for analysis of reward systems, says Shadmehr, because the large number of saccades-2.5 of them per. Second, on average, gives a huge amount of information about our innate preferences.

On the computer screen, the researchers showed images of human faces (which most prefer to focus) as the highest value "reward" and lifeless objects, as a door, as the less-valued reward in different places on the screen. They tracked how quickly researchers participated in focus from one object to another and for how long the object or face held their eyes.

In a subset of 16 of the 92 research participants, researchers also checked the time at which subjects could see an image of a person's face. As the researchers reduced their time to stare, the participants moved their eyes on average faster between the faces.

"For us, the experiment in humans confirms our animal models of optimal foraging, which means that animals, when the environment is rich, tends to move faster between rewards," says Shadmehr.

"Think of kids during Halloween," he says, "when they have a relatively short time to make a neighborhood known for generous candy donors. Most people will drive, not casual stroll, from house to house. "

In another experiment with 17 of the 92 professionals, the researchers showed two pictures on the screen, sometimes a face and sometimes a lifeless object. When the researchers showed more faces, the participants spent less time staring at a single face and more time moving their eyes between the faces.

"This tells us that when the environment is rich (ie more faces), the participants moved not only quickly between the rewards, but spent less time concentrating on each reward," says Shadmehr. He says scientists have observed this phenomenon among collars on the Pacific coast, as feed beaches for clams. They, like the human subjects in computer experiments, used energy to dig for a clam, determine the size and open it only if it was big enough to be worth the effort.

To the researchers' surprise, Shadmehr reports, an experiment failed to match current theories of reward and effort. A group of 22 research participants was shown a series of images placed on larger distances from each other on the screen, which requires more extensive eye movements to focus on each image. In other words, the participants had to spend more effort to get their reward. A dot on the screen indicated where the next image would be displayed.

Conventional wisdom means that in a difficult environment the animals should save their efforts and move more slowly towards rewards. But the opposite happened. Researchers participated more in getting their rewards by moving their eyes twice as fast between pictures of all kinds as they were longer apart than among closer close-ups.

Shadmehr speculates that the unexpected results can be explained by understanding the variations in how some people appreciate certain rewards. "A story of great effort to get a reward can get that reward to seem much more valuable and we will spend more energy to get that reward," says Shadmehr.

The researchers note that there are also differences in differences among individuals. Some people have twice the power of eye movements than others. And the results can also vary with age and gender. Shadmehr says that most people have the fastest eye movements at age 14, on average, and this rate drops with every additional decade of life.

Shadmehr notes that understanding of the principles of power can do far more than tell us about foraging for food or trendy gifts. It can also inform researchers 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, characterized by slower movements as well as sadness and other mood problems.

Shadmehr also suggests that understanding of strength could promote understanding of economic theory, essentially how we make value choices. "The way we identify preference and choice can be measured partly by measuring congenital power," says Shadmehr.

Explore further:
Quick eye movements: A possible indicator for more impulsive decision making

More information:
Tehrim Yoon et al., Controlling Movement and Decision Making during Birth, Test of the National Academy of Sciences (2018). DOI: 10,1073 / pnas.1812979115

Journal reference:
Test of the National Academy of Sciences

Supplied by:
Johns Hopkins University School of Medicine

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