Participants first completed a word reading task in which they were presented with single words (e.g., “移民,“堕胎”)，并被要求判断这个词是政治性的还是非政治性的(通过按下按钮来显示)。. Then the participants watched a series of videos, 其中包括一段新葡京平台堕胎的中立新闻剪辑，以及2016年副总统竞选中新葡京平台警察暴行和移民问题的激烈辩论. During the experiments, the participants’ brain activity was measured using fMRI.

One of the methods the researchers used is called representation similarity analysis. When a person sees a simple, 静态图像, 就像一句话, the brain will represent that word with certain activity patterns.

“You can think of it as the brain representing the word by firing neurons in a certain way,” FeldmanHall说. “这几乎就像一个指纹——一个神经指纹，在大脑中编码这个词的概念.”

She added that since neural activity patterns store information about the world, 大脑如何表现这些信息被认为是一个衡量这些信息如何被解释和用来引导行为和态度的指标.

在研究中, the participants were exposed to words that are often politicized, 像“堕胎,” “移民” and “gangs,” as well as more ambiguous words, 像“自由”.

研究人员通过分析功能磁共振成像(fMRI)数据发现，自由主义大脑产生的神经指纹与其他自由主义大脑产生的神经指纹比保守主义大脑产生的神经指纹更相似, 反之亦然. This is important, FeldmanHall说, because it shows how the brains of partisans are processing information in a polarized way, even when it’s devoid of any political context.

Putting the polarized pieces together to create an ideological story

研究人员还使用了一种被称为神经分割的新方法来探索那些认同特定党派的人的大脑是如何对传入的信息进行偏见解释的. Brains are constantly receiving visual and auditory input, FeldmanHall说, 大脑理解这些连续不断的信息的方式是把它们分成离散的块, 或部分.

“It's like dividing a book of solid text into sentences, paragraphs and chapters,” she said.

The researchers found that the brains of Democrats separate incoming information in the same way, which then gives similar, 这些信息的党派意义——但共和党人的大脑以不同的方式分割相同的信息.

研究人员注意到，拥有相同意识形态的人在观看政治视频时，对政治词汇的神经表征更相似，神经同步性也更强, and segmented real-world information into the same meaningful units.

“两个自由主义者的大脑在观看复杂的视频时会同步，部分原因是每个大脑对政治概念或词语都有神经指纹，这些概念或词语非常一致,” FeldmanHall explained.

这就解释了为什么两个对立的党派可以观看相同的新闻片段，并且都认为这对他们的党派有偏见, 这句话, 图片, 声音和概念在他们的大脑中以不同的方式呈现(但与其他分享他们意识形态的党派相似)。. The stream of information was also segmented out in a different format, telling a different ideological story.

综上所述, the researchers concluded, 研究结果表明，政治意识形态是由在没有任何两极分化议程的环境中处理的政治概念的语义表征形成的, 这些表征会使现实世界的政治信息被解读为两极分化的观点.

就这样, our study provided a mechanistic account for why political polarization arises,” FeldmanHall说.

研究人员现在正专注于如何利用这种对极化的解释来对抗极化.

“The problem of political polarization can’t be addressed on a superficial level,” FeldmanHall说. “Our work showed that these polarized beliefs are very entrenched, and go all the way down to the way people experience a political word. Understanding this will influence how researchers think about potential interventions.”

Additional contributors to this research included Pedro L. 罗德里格斯from the Center for Data Science at New York University and Jeroen M. van Baar from the Netherlands Institute of Mental Health and Addiction.