Narrator: This is Science Today. Living wills are meant to ensure that patients can pass on their end-of-life wishes to loved ones, or surrogates, in the event they are unable to make those decisions themselves. But Peter Ditto, an associate professor of psychology and social behavior at the University of California, Irvine, has found that living wills - also known as advance directives - are not doing the job.
Ditto: The surrogates weren't able to predict patient's wishes any better with an advance directive than without one. And moreover, that even when they had discussions, the surrogates still couldn't predict the patient's wishes any better than they could without a directive.
Narrator: The big question is why surrogates can't predict patients' wishes better.
Ditto: One of the things that we found is sort of a projection bias. That surrogate's predictions typically look more like their own wishes for themselves than they do look like the patient's wishes.
Narrator: Ditto says the point his research makes is to not assume that simply filling out a living will document will accurately communicate one's wishes. Instead, Ditto recommends longer-term discussions. For Science Today, I'm Larissa Branin.