High risk or low: how location on a "risk ladder" affects perceived risk

Our plain-English summary of High risk or low: how location on a "risk ladder" affects perceived risk, by P.M. Sandman, N.D. Weinstein, P. Miller (Risk Analysis, 1994).

The study

• Authors: P.M. Sandman, N.D. Weinstein, P. Miller
• Journal: Risk Analysis
• Published: 1994;14(1):35-45
• Cited by: 52 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Efforts to explain risk magnitude often rely on a "risk ladder" in which exposure levels and associated risk estimates are arrayed with low levels at the bottom and high ones at the top. Two experiments were conducted to test the hypothesis that perceived threat and intended mitigation vary with the location of the subject's assigned level on the risk ladder. Subjects were New Jersey homeowners, asked to assume a particular level of radon or asbestos contamination in their homes, to read a brochure explaining the risk, and then to complete a questionnaire. Both studies found that the difference between an assigned level one-quarter of the way up the ladder and the same level three-quarters of the way up the ladder significantly affected threat perception; the effect on mitigation intentions was significant in only one of the studies. Variations in assigned risk also affected threat perception and mitigation intentions. Variations in test magnitude (e.g., 15 fibers per liter vs. 450 fibers per cubic foot, roughly equivalent risks) had no effect, nor did the distinction between radon and asbestos affect the dependent variables. These findings suggest that communicators can design risk ladders to emphasize particular risk characteristics.

In plain English

This article reported two experiments on how displaying asbestos and radon risks affected perceived threat; it did not measure anyone's actual exposure or health. Homeowners from Middlesex County, New Jersey (449 in the first study, 534 in the second) imagined a home test result, read a brochure showing that result on a "risk ladder" with cancer death estimates and smoking comparisons, and answered questions. In both studies, placing the same asbestos result three-quarters rather than one-quarter of the way up the ladder raised scores on a perceived-threat index (11.46 versus 12.95 in Study One; 11.58 versus 14.28 in Study Two). The effect on intentions to spend $1000 on reducing the level was statistically significant only in Study Two. Expressing asbestos in fibers per cubic foot instead of fibers per liter made no significant difference. Higher stated risk raised perceived threat in both studies. Radon and asbestos shown at nearly the same risk and ladder position drew no significant difference in perceived threat or mitigation intentions. The authors concluded that the locational hypothesis was confirmed in both experiments.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Two questionnaire-based risk-communication experiments. Each used a single-factor, between-subjects design with four brochure formats, and each subject received one format. Subjects responded to hypothetical home test results, not real measurements.
• Who was studied: Homeowners aged 18 or older who had not previously tested their homes, selected randomly from telephone listings in central New Jersey (Middlesex County). Study One had 449 subjects: 2488 were reached and qualified, 753 (30.3%) agreed, and 59.6% of those returned a questionnaire. Study Two had 534 subjects: 3241 were contacted, 972 (30.0%) agreed, and 54.9% returned a questionnaire. No study dates are given.
• Exposure: No real exposure was studied. Subjects were assigned hypothetical home test results. In Study One these were asbestos only: 15.0 fibers per liter, 450 fibers per cubic foot, or 15.0 fibers per deciliter. In Study Two they were asbestos at 25 fibers per liter or 60 fibers per deciliter, or radon at 25 picoCuries per liter. Each result was shown on a risk ladder with extra cancer deaths per 1000 people and cigarette comparisons. These risk figures were brochure content, not study findings.
• Main results:
  • Study One (asbestos only): the same result placed higher on the ladder (Displaced format) produced greater perceived threat than the Base format, 12.95 vs. 11.46, p less than .01.
  • Study One: the effect of displacement on mitigation intentions was in the same direction but not statistically significant.
  • Study One: expressing the result in fibers per cubic foot instead of fibers per liter (a 30-fold larger number for the same risk and ladder position) produced no significant differences in perceived threat or mitigation intentions.
  • Study One: a 10-fold higher stated risk (High Risk format) gave higher perceived threat than the Base format, 13.24 vs. 11.46, p less than .01. Mitigation intentions did not differ significantly between these two formats.
  • Study One: the High Risk format was associated with greater perceived threat than the High Test Magnitude format (13.24 vs. 10.58, p less than .001) and greater interest in mitigation (3.95 vs. 3.25, p less than .001).
  • Study One: the Displaced and High Risk formats did not differ significantly. The authors judged a 10-fold increase in risk to be roughly equivalent to a half-ladder displacement.
  • Study Two: with risk and ladder position held nearly constant (Base Radon vs. High Risk Asbestos), there were no significant differences between radon and asbestos in perceived threat or mitigation intentions.
  • Study Two: a half-ladder displacement of the same asbestos result raised perceived threat from 11.58 (Base Asbestos) to 14.28 (Displaced Asbestos), p less than .001.
  • Study Two: displacement also significantly raised mitigation intentions, 3.32 for Base Asbestos vs. 3.79 for Displaced Asbestos, p less than .01.
  • Study Two: at the same ladder position, the 24-fold higher asbestos risk gave higher perceived threat, 17.97 for High Risk Asbestos vs. 14.28 for Displaced Asbestos, p less than .001.
  • Study Two: High Risk Asbestos also gave greater mitigation intentions than Displaced Asbestos, 4.22 vs. 3.79, p less than .01.
  • Study Two: asbestos was rated as more difficult to reduce than radon (means 4.04 vs. 3.23, p less than .001), as less unfamiliar, and as less natural. Ratings of dread and lethality did not differ significantly between the two hazards.
• The authors' conclusion: The authors concluded that the locational hypothesis was confirmed in both experiments: where a result appeared on the risk ladder affected perceived risk. They wrote that communicators can design ladders to emphasize particular risk characteristics.
• Limitations the authors state:
  • The authors suggested the smaller effects on mitigation intentions may reflect the lower reliability of a single-question measure.
  • Both tests used ladders that included numerical risk information and smoking comparisons. The effect of position on a purely visual ladder is not known.
  • The locational effect may depend on the risks shown at the ends of the ladder, not only on the subject's own level.
  • The finding of no test-magnitude effect may not apply when actual risk is lower and the numbers are higher and less familiar.
  • Mitigation was measured as stated intention to spend $1000, not actual behavior.

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