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Communicating environmental risks: Clarifying the severity effect in interpretations of verbal probability
1Department of Cognitive, Perceptual and Brain Sciences, University College London, London WC1H 0AP, United Kingdom. adam.harris@ucl.ac.uk
Summary
People interpret verbal probability expressions differently based on event severity. Severe events are perceived as more probable than neutral events, impacting risk communication.
Area of Science:
- Psychology
- Risk Communication
- Decision Science
Background:
- Verbal probability expressions are crucial for communicating risks, notably by organizations like the Intergovernmental Panel on Climate Change (IPCC).
- Understanding public interpretation of these expressions is vital for effective risk mitigation strategies.
- Previous research had suggested outcome severity did not influence probability interpretation, a finding potentially based on flawed methodology.
Purpose of the Study:
- To investigate the impact of event severity on the interpretation of verbal probability expressions.
- To challenge and correct previous findings regarding outcome severity's influence on probability perception.
- To provide a clearer understanding of how individuals process risk information conveyed through language.
Main Methods:
- Three studies were conducted using a novel manipulation of event severity, distinct from event base rates.
- Participants interpreted verbal probability expressions within scenarios related to climate change, nanotechnology, and nuclear materials.
- The experimental design aimed to isolate the effect of severity on probability interpretation.
Main Results:
- A systematic effect of event severity on the interpretation of verbal probability expressions was demonstrated.
- Expressions associated with severe events were consistently interpreted as indicating higher probabilities compared to those linked to neutral events.
- This finding held across diverse risk contexts, including climate change, nanotechnology, and nuclear risks.
Conclusions:
- Outcome severity significantly influences the interpretation of verbal probability expressions.
- This study provides the first direct evidence of severity's effect, correcting prior conclusions potentially stemming from methodological limitations.
- Accurate interpretation of risk communication requires accounting for the perceived severity of potential outcomes.
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