Customers are more likely to buy something if they hear about it via Twitter than if they read about it on Facebook or from a company e-mail, a new survey has found. Digital marketing firm ExactTarget surveyed British customers and found that 32% were more likely to buy something after they followed a company on Twitter, compared with 24% who would buy after "liking" the firm on Facebook or 21% who bought after subscribing to a company's e-mail list.