Nav: Home

How we make decisions depends on how uncertain we are

September 09, 2019

A new Dartmouth study on how we use reward information for making choices shows how humans and monkeys adopt their decision-making strategies depending on the uncertainty of information present. The results of this study illustrated that for a simple gamble to obtain a reward, when the magnitude or amount of the reward is known but the probability of the reward is unknown and must be learned, both species will switch their strategy from combining reward information in a multiplicative way (in which functions of reward probability and magnitude are multiplied to obtain the so-called subjective value) to comparing the attributes in an additive way to make a decision. The findings published in Nature Human Behavior, challenge one of the most fundamental assumptions in economics, neuroeconomics and choice theory that decision-makers typically evaluate risky options in a multiplicative way when in fact this only applies in a limited case when information about both the magnitude and probability of the reward are clearly known.

"This is the first cross-species study using similar experimental design to show that both humans and monkeys change their strategy when they go from choice under risk (when reward probabilities are known) to choice under uncertainty (when reward probabilities are unknown and must be learned), from combining information in a multiplicative way to comparing information in an additive way," said senior author Alireza Soltani, an assistant professor of psychological and brain sciences at Dartmouth. "Comparing reward attributes may seem like comparing apples to oranges; however, when you compare different pieces of reward information rather than combine them, you become a more flexible decision-maker," he added.

The team of researchers from three universities found that when the probability of the reward must be learned (but the magnitude of reward is provided), as the environment becomes more uncertain both humans and monkeys would more often opt for bigger but more risky options by putting less weight on the probability and more weight on the magnitude of the reward. The team also examined neural activity in the monkeys' brain during the task and found a correlation between this adjustment in behavior and how prefrontal neurons represents reward information. Specifically, consistent with the behavior, neurons in the dorsolateral prefrontal cortex represented magnitude more strongly in a more uncertain environment when more weight was put on magnitude.

To understand the findings, consider the following hypothetical scenario (not part of the actual methods used in the research). Pretend it's your lucky day where you could win money in a free sweepstakes. All you need to do is pick a ticket from one of two bowls: Bowl 1 contains 99 winning tickets each valued at $100 and 1 ticket with $0 value. Bowl 2 contains 50 winning tickets valued at $250 and 50 tickets with $0 value. Which bowl do you choose from? Most people will pick Bowl 1 because humans are risk averse. Bowl 1 offers a better combination of properties, even though Bowl 2 could be more lucrative. In order to decide which option to go with, you probably came up with a subjective value for each of the two bowls by multiplying the probability of winning and the subjective utility or desirability of the winning tickets.

Consider another scenario where you only know the dollar amount of the winning tickets in each bowl but don't know the probability of picking a winning ticket. However, you have been observing people who have been choosing tickets from the two bowls before you and have learned that Bowl 1 almost always gives $100 winning tickets but Bowl 2 gives $250 winning tickets only half the time. In this uncertain scenario, you probably choose the bowl that you think is better by comparing how often the two bowls have been awarding winning tickets relative to the amounts of winning tickets they award. In this scenario, as the decision-maker, you used an additive strategy because you compared reward information across the two options rather than trying to combine it.

For the actual study, a series of gambling tasks were administered on a computer for which monkeys and human participants had to choose from two options. Humans (Dartmouth undergraduate students) were awarded a combination of points that were converted to money and extra credit for a course, and monkeys (studied at Yale School of Medicine and University of Minnesota) were awarded with drops of juice according to their choices and the outcomes of the gambles.

"Speaking more broadly, our results show that in an uncertain reward environment, which is the case most of the time, we may not construct the so-called subjective value as prescribed by normative models of choice, and that flexibility is more important than being rational or optimal," added Soltani.
-end-
Soltani is available for comment at: alireza.soltani@dartmouth.edu.

The study was co-authored by Shiva Farashahi at Dartmouth, Christopher H. Donohue at the Gladstone Institutes who was formerly at Yale School of Medicine, Benjamin Y. Hayden at the University of Minnesota, and Daeyeol Lee at Johns Hopkins University who was previously at Yale School of Medicine.

Dartmouth College

Related Behavior Articles:

I won't have what he's having: The brain and socially motivated behavior
Monkeys devalue rewards when they anticipate that another monkey will get them instead.
Unlocking animal behavior through motion
Using physics to study different types of animal motion, such as burrowing worms or flying flocks, can reveal how animals behave in different settings.
AI to help monitor behavior
Algorithms based on artificial intelligence do better at supporting educational and clinical decision-making, according to a new study.
Increasing opportunities for sustainable behavior
To mitigate climate change and safeguard ecosystems, we need to make drastic changes in our consumption and transport behaviors.
Predicting a protein's behavior from its appearance
Researchers at EPFL have developed a new way to predict a protein's interactions with other proteins and biomolecules, and its biochemical activity, merely by observing its surface.
Spirituality affects the behavior of mortgagers
According to Olga Miroshnichenko, a Sc.D in Economics, and a Professor at the Department of Economics and Finance, Tyumen State University, morals affect the thinking of mortgage payers and help them avoid past due payments.
Asking if behavior can be changed on climate crisis
One of the more complex problems facing social psychologists today is whether any intervention can move people to change their behavior about climate change and protecting the environment for the sake of future generations.
Is Instagram behavior motivated by a desire to belong?
Does a desire to belong and perceived social support drive a person's frequency of Instagram use?
A 3D view of climatic behavior at the third pole
Research across several areas of the 'Third Pole' -- the high-mountain region centered on the Tibetan Plateau -- shows a seasonal cycle in how near-surface temperature changes with elevation.
Witnessing uncivil behavior
When people witness poor customer service, a manager's intervention can help reduce hostility toward the company or brand, according to WSU research.
More Behavior News and Behavior Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at Radiolab.org/donate.