Author Archives: ysohn

The New Science of Culturomics

By Yunkyu Sohn

Using a corpus of digitalized texts of The Google Books Project (i.e. the offline version of Google Trends), Michel et al. (2011) propose a new approach for quantitative investigation of culture. Their method may have broad impacts on various disciplines such as “lexicography, the evolution of grammar, collective memory, the adoption of technology, the pursuit of fame, censorship, and historical epidemiology.”


Game Theory of Mind

by Yunkyu Sohn

Traditional game theory assumes that the level of recursive belief inference is infinite when people choose their strategy as a result of guessing the others’ strategies. For example, in Keynesian beauty contest where all participants are asked to pick a number between 0 and 100 and win if one is the closest to 2/3 of population average, Nash equilibrium predicts all players should chose 0 since recursive inference about others’ preference will decrease the value of your choice, and eventually reach the minimum possible value. However studies in behavioral economics have found that the degree of recursion is bounded to smaller values.

By running a 2 dimensional stag-hunt game, recent fMRI experimental study done by Yoshida et al. demonstrates that people vary their level of inference depending on their partner’s past strategic profiles. Imaging result shows that prefrontal cortex region is subdivided by its roles for encoding uncertainty of inference of partner’s strategy and inferring the degree of recursive inference.

Drawing Interactions

Pulse of the Nation

by Yunkyu Sohn

Population dynamics of human emotion has clear cycles!

Workshop on Social Media Analytics

Workshop on Social Media Analytics will be held on July 25, 2010 in Washington, DC in conjunction with The 16th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining (KDD 2010).

Hand Washing Diminishes Cognitive Dissonance Effect

by Yunkyu Sohn

What we do when we confront multiple contradicting ideas? The theory of cognitive dissonance asserts that people tend to manipulate their preference, attitude or opinion to evade such uncomfortable situations. Psychologists developed a standard experimental setup to assess the presence of such tendency. In this setup, the experimenter asks subjects to rank N objects according to their preference and offers n<N objects to them. After the transaction was made the subjects are asked to re-rank N products. Many experimental studies have found that the subjects are likely to alter their preference ordering. That is, they tend to rank those n objects higher afterward. Two fMRI studies (Sharot, Martino and Dolan 2009; Veen et al. 2009) revealed that dorsal anterior cingulate cortex anterior insula, caudate nucleus and amygdala underly certain behavior.

In a recent Brevia published in Science, Lee and Schwarz report that ordinary hand washing task removes the consequential preference shift caused by cognitive dissonance. This study extends the findings of previous studies which examined the role of physical cleansing on compensatory behavior and moral judgement, and demonstrates that it also has implications on people’s preference consistency. The link found in these works may elucidate result of voters’ physical and physiological activities on their political attitudes and decisions (see Mullainathan and Washington on cognitive dissonance in voting).

Does moral action depend on reasoning?

An interesting set of discussions by leading scholars in moral psychology: