Dr. Michael Greger’s Bias Is Food for Thought - McGill University

How old do you think you will live to be? Your answer may be more revealing than you realize. A study that tracked older adults in Japan for up to 28 years suggests people have a surprisingly accurate sense of their own longevity. Those who expected to live longer generally did. But their predictions showed one striking bias: many underestimated how much time they had left. Among participants whose outcomes could be determined, the researchers report that approximately 59 percent outlived their expected lifespan. Led by social scientist Shohei Okamoto of the University of Tsukuba, the team analyzed data from the Japanese Aging and Health Dynamics Study, a nationally representative survey of adults aged 60 and older across Japan. In 1996, 2,447 participants were asked what age they expected to reach. Of those, 393 said they did not know. The remaining 2,054 gave an age ranging from 63 to 120. Over the next 28 years, 1,514 of those who supplied an estimate died.