Saturday, February 27, 2010

How Do People Value Life?

This is an interesting look at how our culture prioritizes human life.


Who should be saved when health resources are limited? Although bioethicists and policymakers continue to debate which metric should be used to evaluate health interventions, public policy is also subject to public opinion. We investigated how the public values life when evaluating vaccine-allocation policies during a flu epidemic. We found that people’s ratings of the acceptability of policies were dramatically influenced by question framing. When policies were described in terms of lives saved, people judged them on the basis of the number of life years gained. In contrast, when the policies were described in terms of lives lost, people considered the age of the policy’s beneficiaries, taking into account the number of years lived to prioritize young targets for the health intervention. In addition, young targets were judged as more valuable in general, but young participants valued young targets even more than older participants did.

Imagine having to choose between saving the life of a young person or an old person. Although painful, such decisions are inherent in the appropriation of scarce resources for public- health initiatives. For example, in the event of pandemic flu, who should receive the limited supply of vaccines and antiviral medication (Emanuel & Wertheimer, 2006)? These decisions entail, even if only implicitly, the prioritization of certain individuals’ lives over others. Are all lives equally valuable, and if not, whose lives are more valuable?

In the current article, we put aside the important issues of risk (who is at highest risk of dying?) and efficacy (for whom is the intervention most effective?; Galvani, Medlock, & Chapman, 2006) and instead focus on how people quantify the outcome of health interventions—the metric for valuing life. Potential metrics include the number of lives saved, the number of life years gained, and the number of quality-adjusted life years (QALYs) gained (Pliskin, Shepard, & Weinstein, 1980). These metrics imply different optimal policies. The number-of-lives metric requires that the optimal policy maximize the number of individuals being saved, assuming no priority in saving certain individuals over others. Under a life-years-saved metric, however, one would prioritize younger individuals, to the extent that they have a greater number of years left to live. Some government agencies, such as the Food and Drug Administration, use life years saved to quantify benefits (U.S. Food and Drug Administration, 2006). The QALYs metric is similar but assigns greater value to lives of healthy compared with ill individuals, given the same life expectancy, and greater value to interventions that improve quality of life.

Bioethicists and public-health policymakers have extensively debated which metric to adopt (Evans, 1997; Williams, 1997a, 1997b). The controversy reflects the inherently moral nature of placing a value on life. Aside from these debates, if we accept that public-health policies should reflect the moral values of the public, it is critical to understand how the public thinks life should be valued and the underlying mechanisms that give rise to these value judgments. Such an understanding is also relevant to the debate on what kinds of inequities constitute ageism in health care (Kane & Kane, 2005).

Previous studies indicate that the public values the lives of young people more than those of older people (Busschbach, Hessing, & de Charro, 1993; Cropper, Aydede, & Portney, 1994; Johannesson & Johansson, 1997; Lewis & Chamy, 1989; Ratcliffe, 2000; Rodriguez & Pinto, 2000; Tsuchiya, Dolan, & Shaw, 2000). People may value young people more than older people for a number of reasons (Rodriguez & Pinto, 2000). Not only do young people have more years left to live, and thus receive more benefit from a lifesaving intervention, they also have fewer years lived so far and thus deserve their “fair innings” (Williams, 1997a). For example, a 20-year-old has about 3 times as many years left as a 60-year-old (assuming an average life expectancy of 80 years); however, saving one 20-year-old is viewed as equivalent to saving seven 60-year-olds (Cropper et al., 1994), which indicates greater value for younger individuals even beyond what the life-years-saved metric would predict. This response pattern may stem from a sentiment that the death of a younger person is perceived as more tragic and unjust than the death of an older person (Chasteen & Madey, 2003). A similar message is conveyed in the Chinese saying, “Nothing is sadder than for the gray-haired to see the dark-haired go.”

Do people use a years-left metric, a years-lived metric, or a combination of both, to value life? Under normal circumstances, years left (equivalent to remaining life expectancy) is almost perfectly correlated with years lived (equivalent to age), making it impossible to separate these two bases of evaluating life. In our study, we disentangled years left from years lived by manipulating the life expectancy of individuals in a hypothetical scenario, where individuals of various ages were described as either having a normal life expectancy or having only 2 years left due to a preexisting health condition.

If a years-left metric is adopted, value of life should be a negative linear function of age for individuals with normal life expectancy (because years left depends on age) but should not vary by age for individuals with a fixed 2 more years to live (because years left is independent of age). However, if a years-lived metric is adopted, value of life should be a negative linear function of age (years lived is age), regardless of whether the individuals are expected to live to a normal life expectancy or only 2 more years.

We explored whether the metric people use to evaluate life is influenced by how the question is asked. Past research on decision making has demonstrated the powerful influence of question framing (Tversky & Kahneman, 1981)—two equivalent descriptions can lead to very different preferences. Framing can even influence moral behavior (Kern & Chugh, 2009). We hypothesized that “lives saved” and “lives lost” frames would not merely alter preference between options, as shown in previous studies, but would actually invoke different psychological processes or strategies for evaluating lifesaving interventions.

Specifically, we expect the “lives saved” frame to prompt people to evaluate the benefits of the lifesaving interventions and focus on what the victims stand to gain: the number of life years they are expected to gain from the intervention. In contrast, the “lives lost” frame is expected to prompt people to consider what the victims stand to lose: the loss of life. Consequently, we hypothesize that in the “lives saved” frame, people will use a years-left metric, judging younger victims as more valuable only when they have more years left to live; and those in the “lives lost” frame will adopt a years-lived metric, judging younger victims as more valuable regardless of number of years left, because the death of a young person feels more tragic than the death of an older person (Chasteen & Madey, 2003).

The rest of this article is available online

Lil, Meng; Vietril, Jeffrey; Galvani, Alison and Chapman, Gretchen B. 2009. "How Do People Value Life?". Psychological Science. Posted: December 22, 2009. Available online:

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