Medical decision making: lessons from psychology.

A wide variety of psychological mechanisms can interfere with clear thinking as patients make choices among risky treatments. The availability heuristic can make some outcomes seem more likely than they really are, the way treatment options are framed and presented can radically affect choice, the placement of a patient's reference point between gains and losses can create a bias towards caution or risk-taking, outcomes that seem certain may make a greater impression than probable or improbable ones, highly-desired benefits can obscure very real risks (and vice versa), and denial mechanisms may render a doctor's best efforts at communication virtually worthless.