Retailers and manufacturers of consumer goods have long believed that most grocery store purchases are unplanned, and that showy displays will push more goods into shopping carts. The displays may help sales, but the underlying assumption--that most grocery store sales are impulse buys--is wrong. That's not to say that in-store marketing is unimportant. But retailers may need to rethink strategies for it. Researchers have found that certain traits of shoppers, including age, income and their particular shopping style, have a greater effect on making unplanned purchases than does the store or environment.
Source: Wharton Business School