As the insurance exchanges get up and running, carriers are offering narrow packages designed to keep costs down — something everyone assumes consumers want.

A massive survey by a team of Booz & Co. researchers, however, clearly shows consumers are instead drawn as much by the narrowness of their choices as by the low cost.

"Many studies have concluded that consumers will be highly price-sensitive when they shop on insurance exchanges. In response, insurers have created new products that keep prices down by aggressively limiting the doctors and hospitals where patients can go for care. Not surprisingly, these so-called 'narrow' networks have been met with sharp criticism from advocacy groups, reform skeptics, and providers," authors Sanjay B. Saxena and Nate Holobinko write in a blog post on the Harvard Business Review.