Insensitivity to the Value of Human Life: A Study of Psychophysical Numbing

A fundamental principle of psychophysics is that people's ability to discriminate change in a physical stimulus diminishes as the magnitude of the stimulus increases. We find that people also exhibit diminished sensitivity in valuing lifesaving interventions against a background of increasing numbers of lives at risk. We call this psychophysical numbing. Studies 1 and 2 found that an intervention saving a fixed number of lives was judged significantly more beneficial when fewer lives were at risk overall. Study 3 found that respondents wanted the minimum number of lives a medical treatment would have to save to merit a fixed amount of funding to be much greater for a disease with a larger number of potential victims than for a disease with a smaller number. The need to better understand the dynamics of psychophysical numbing and to determine its effects on decision making is discussed.