Opinion dynamics

Using social media data to test psychological theories

Social media data presents us with an unparalleled opportunity to study human psychology on a large scale and in arguably more realistic settings than the psychological sciences have historically been afforded. This raises the question of whether analysis of the text generated by social media users can be used to assess the accuracy of psychological theories, which have largely been developed on the basis of experiments performed under artificial or hypothetical circumstances. In this project, we used tweets generated by millions of Twitter users during the COVID-19 pandemic to try to assess the accuracy of the theory of psychophysical numbing, which may be summarised informally with the phrase: “the more who die, the less we care”. Our approach can be used to track the public’s reactions to evolving crises, such as the COVID-19 pandemic, and therefore to guide communication with the public during crisis scenarios by monitoring indicators of the public’s perception of risk in near-to-real-time.

Key findings:

• We found evidence of psychophysical numbing: the Twitter users we analysed increasingly fixated on mortality, but in a decreasingly emotional and increasingly analytic tone.
• The average attention afforded to national Covid-19 mortality rates is modelled accurately with the Weber–Fechner and power law functions of sensory perception that have previously been proposed in the psychological literature. Our parameter estimates for these models are consistent with estimates from psychological experiments, and indicated that users in this dataset exhibit differential sensitivity by country to the national Covid-19 death rates.

Funders include:

EPSRC Centre for Doctoral Training in Industrially Focused Mathematical Modelling (EP/L015803/1) in collaboration with Improbable, Conacyt-SENER: Sustentabilidad Energética scoloraship

Quantifying social contagion in stock market movements

Social media has changed the fabric of society. Polarisation, the spread of fake news, and other societal challenges are some of its documented consequences. As many as 4.20 billion people, or 53.6% of the world population, are active social media users, each just a few clicks away from the next popular phenomenon. Now, a growing audience turns to social media for promising stock market gambles.

Our research sheds light on the social dynamics driving a new way of investing. In particular, we use text data from the r/WallStreetBets site to­ ­follow the investment choices users talk about, and who they talk with. r/WallStreetBets started its ascent to popularity in 2015, incidentally the same time the popular trading app Robinhood became available.

Key findings:

• Excitement about tickers and the direction that individuals choose to trade (buy / sell) spreads through social contagion from one user to another
• A theoretical model, underpinned by social contagion, predicts an initial price increase for an asset, from the asset’s growing popularity, followed by a volatile crash
• We validate the existence of a causal link between WallStreetBets activity and the stock market