title: Communicating environmental risks: Clarifying the severity effect in interpretations of verbal probability expressions.
abstract: Verbal probability expressions are frequently used to communicate risk and uncertainty. The Intergovernmental Panel on Climate Change (IPCC), for example, uses them to convey risks associated with climate change. Given the potential for human action to mitigate future environmental risks, it is important to understand how people respond to these expressions. In 3 studies employing a novel manipulation of event severity (so as to avoid any confound with event base rate), we demonstrated a systematic effect of event severity on the interpretation of verbal probability expressions. Challenging a previous finding in the literature, expressions referring to a severe event were interpreted as indicating a higher probability than those referring to a more neutral event. The finding was demonstrated in scenarios communicating risks relating to climate change (Studies 1 and 2) and replicated in scenarios involving nanotechnology and nuclear materials (Study 3). This is the first direct demonstration of an effect of outcome severity on the interpretation of verbal probability expressions, correcting a previous (potentially problematic) conclusion attributable to a flawed experimental design.
authors.affiliation: Department of Cognitive, Perceptual and Brain Sciences, University College London, London WC1H 0AP, United Kingdom. adam.harris@ucl.ac.uk
authors.forename: Adam J L
authors.initials: AJ
authors.lastname: Harris
authors.forename: Adam
authors.initials: A
authors.lastname: Corner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D004777:Environment; D005260:Female; D006801:Humans; D007258:Informed Consent; D008297:Male; D008875:Middle Aged; D010817:Physician-Patient Relations; D011336:Probability; D018570:Risk Assessment; D014342:Truth Disclosure; D014705:Verbal Behavior; D055815:Young Adult