Zeroing in on college students makes sense for Instagram and Tinder, experts say. Both platforms enjoy tremendous popularity among young adults and these features could help them expand their user bases — and keep people from moving on to competing platforms. “User attention is divided basically more than ever before. There are apps for networking, dating … news, shopping and entertainment,” said Lalin Anik, a marketing expert at University of Virginia’s Darden School of Business who studies the impact of social connection on consumer behavior. “Social media giants are seeking novel ways to at...