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[2020/08/20] Why Do We Always Make Mistakes? NYMU Institute of Neuroscience Discovered the Mechanism behind “Guessing”

Associate Professor Wu (middle) used fMRI to discover the mechanism behind probability estimation

 

National Yang-Ming University Institute of Neuroscience Associate Professor Wu and his team have discovered that “comparison” is a key factor that impacts on the brain’s probability of produce an error. Through a series of lottery ticket experiments, combined with functional magnetic resonance imaging and a neural computing model, they have identified the basic mechanism behind how our brain reacts to uncertainty. During times of uncertainty, our brain is more prone to being influenced by psychological conditions. Their results show that our brain either over-estimates or underestimates the circumstances behind the choice, which leads to wrong decisions.

 

The experiment consists of 34 subjects that had their brain activities recorded using magnetic resonance imaging while playing a game involving lottery tickets. The subjects encountered six lottery coupons during the experiment. Each of the six coupons had either a 10%, a 50%, or a 90% chance of winning the lottery. The subject was only able to estimate the probability of winning by constantly playing the lottery. Surprisingly, even if the true probability of winning a lottery ticket is 50%, subjects who had experienced more 10% lottery tickets, that is low winning odds lottery tickets, in a short period of time, tended to overestimate the winning probability of a given lottery ticket; on the other hand, subjects whom experience more 90% lottery tickets, that is high winning odds lottery tickets, tended to underestimate their chance of winning. Thus this kind of “context effect” has an impact on the brain’s probability assessment only during times of ambiguity, such as, in this experiment, when there is a 50% chance of winning. Under such conditions people are more likely to fall into the quagmire of comparison and form poor decisions.

 

     

  The first author of the paper, student Lin is currently pursuing his doctoral degree in Switzerland (left); the second author of the paper is Stanford University Psychology Professor Justin Gardner (right)

 

 

In addition, the research team also found that, using functional magnetic resonance imaging, the ventromedial prefrontal cortex, dorsal anterior cingulate cortex, and right medial parietal sulcus (right intraparietalsulcus) are areas of the brain that are more significantly affected by such situational effects. The research team than used machine learning analysis methods and found that the activities of these three brain regions are able to accurately predict how each of the subjects respond differently to these probability situations.

 

Associate Professor Wu, who led the research, said “although the brain is a very powerful computing machine, one of its imperfections is that it is easily manipulated by context. The reason why situations can be a factor that impacts on outcome lies in two key elements. One is uncertainty, and the other is comparison. When we are more uncertain about whether something will happen, the brain becomes more susceptible to influences related to the situation. This results in an overestimating or an underestimating of the probability of a given outcome. In addition to having an impact on daily decision-making, this experiment will have a significant impact on many industries and public policies that rely on probability or risk assessment”.

 

This experiment was a joint effort between National Yang-Ming University and Stanford University. This experiment is the first to discover the neurological mechanism behind probability estimation, and was published in the international journal, PLOS Biology.

 

 

 

 

 

 

 

 

 

 


 

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