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Scientists have known for a long time that we are overwhelmed by too many choices. Colin Camerer, a professor at Caltech, and his co-authors have discovered what is happening in our brain.
Brain regions reflecting the value defined in the choice: the areas indicated in red to yellow show a linear increase in fMRI activity as a function of S during the exposure phase of grouped choice tests. Image credit: Reutskaja et al, doi: 10.1038 / s41562-018-0440-2.
"In many modern economies, consumers have a vertiginous range of choices, even for simple products such as bottled water," said Professor Camerer and his colleagues.
"A typical American supermarket can hold more than 30,000 items, including 285 types of biscuits and 275 types of cereals. For important choices during life, such as investment decisions for retirement, one can be faced with dozens, even hundreds of options, with serious consequences if taking decision is postponed or totally avoided. "
"Current models of choice overload derive mainly from behavioral studies. A neuroscience investigation could shed more light on these models by revealing hidden mental processes during decision-making. "
"We explored the overload of choice using functional magnetic resonance imaging (fMRI) as subjects chose sets of different sizes or scanned them."
As part of this study, images of picturesque landscapes that they could print on an article such as a cup of coffee were presented to the volunteers.
Each participant has been offered a series of sets of images containing six, 12 or 24 images.
They were asked to make their decisions while an fMRI machine was recording activity in their brain.
As a control, they were asked to browse the images again, but this time, their selection of images was done randomly by a computer.
The fMRI examinations revealed brain activity in two regions as participants made their choices: the anterior cingulate cortex (ACC), where the potential costs and benefits of decisions are weighted, and the striatum, a part of the brain responsible for the determination. value.
Professor Camerer and his co-authors also found that activity in these two regions was highest among subjects who could choose among 12 options and the lowest in subjects with six or 24 elements.
The activity pattern likely results from the interaction of the striatum and the CAC and the weighting of the increasing reward potential (getting an image that they really appreciate for their cup) compared to the increasing amount of work that the brain will have to to evaluate the possible outcomes.
As the number of options increases, the potential reward increases and then begins to stabilize due to diminishing returns.
"The idea is that the best out of 12 is probably pretty good, while the jump to the best out of 24 is not a big improvement," said Professor Camerer.
"At the same time, the amount of effort required to evaluate options is increasing."
"Together, the mental effort and the potential reward create a waiting area where the reward is not too low and the effort is not too high. This trend was not observed when the subjects simply scanned the images because there was no reward potential and therefore less effort was needed to evaluate the options. "
"12 is not a magic number for human decision making, but rather an artifact of the experimental design," he said.
"The ideal number of options for a person is probably between 8 and 15, depending on the perceived reward, the difficulty of evaluating the options and the individual characteristics of the person."
The results were published in the journal Nature human behavior.
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Elena Reutskaja et al. Overload of choice reduces the neuronal signatures defined by choice in the dorsal striatum and anterior cingulate cortex. Nature human behavior, published online on October 1, 2018; doi: 10.1038 / s41562-018-0440-2
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