Speaker: Dr Adam Harris, UCL

Title: THE PREVALENCE & CONSEQUENCES OF THE SEVERITY EFFECT IN PROBABILITY COMMUNICATION 

Abstract:: Effective decision making relies on reliable assessment of probabilities (‘will this talk be stimulating?’). Frequently, we receive clues to these probabilities from expert sources, be they professionals (e.g., weather forecasters) or colleagues (e.g., those who have seen me talk before). Probabilities can be communicated in different formats, including verbal (‘it is likely that it will rain tomorrow’). Such verbal communications are susceptible to a variety of pragmatic influences, and in the current talk we focus on the Severity Effect, whereby numeric interpretations of verbal probability expressions (VPEs) are higher for more severe events. We extend this research by demonstrating that professional weather scientists provide higher verbal probability expressions for severe impacts with the same numerical probabilities as non-severe impacts, in a hypothetical weather warning task. Finally, probability estimates are seen to increase across ‘rounds’ of a communication chain study, where VPEs are translated to numbers and vice versa, across seven rounds. The research has implications for likely amplification of perceived risks.

Host: Dr Emmanouil Konstantinidis

For Teams Link, contact: Catherine Johnstone

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