ANN ARBOR—Suggestions from close friends about what they think we would like” movies, books, restaurants” may not be as helpful as we think, says a University of Michigan marketing professor.

A new study by Andrew Gershoff of U-M’s Ross School of Business and colleague Gita Johar of Columbia University finds that estimates of close friends’ knowledge about our preferences are less accurate than that of acquaintances” in other words, we tend to overestimate how well our friends know us.

Appearing in this month’s Journal of Consumer Research, the three-part study,” Do You Know Me? Consumer Calibration of Friends’ Knowledge,” examines how well people think their friends know them by asking about their tastes in movies and restaurants.

“Think your friends know you pretty well? Think again,” said Gershoff, U-M associate professor of marketing.” We make our worst estimates for our closest friends. This is important because it affects how willing we are to rely on our friends’ advice and word-of-mouth recommendations.”

Gershoff and Johar say that overestimates of close friends’ knowledge appear to be driven by motivation to maintain and protect close relationships.

“To maintain our self-image, we want to believe that we are important to others, particularly those we care about,” Gershoff said.” So when we think about our close friends, we are more motivated to think they know us well compared to our less close friends, and so we overestimate more for our close friends.”

Although we, as consumers, may over-rely on close friends, we may be better off as a result, the researchers say. For example, recommendations from friends provide an opportunity to learn about one’s own tastes and preferences. Further, accepting a recommendation may enhance a relationship in much the same way as accepting a gift does.

“Potentially, the benefit of maintaining a close relationship is worth the cost of over-relying on a friend,” Gershoff said.

Business SchoolAndrew Gershoff