He spoke with Norway manager Age Hareide, who spent time with Manchester City and Norwich as a player, before making his decision to move to the JJB Stadium on loan from Russian side Zenit St Petersburg.
"I spoke to the national coach who knows Steve Bruce very well and he said not only was he a great manager but a great human being," Hagen told Wigan's official website. "Steve Bruce is a good guy and it was very easy for me to say yes once I had spoken to him on the telephone.
"Every footballer in the whole world would love to come to England and play in the Premier and I am no different.
"I just want to play well for Wigan and work hard to maintain the club's Premier League status."
Hagen, who has 28 caps for Norway, was Bruce's final signing of a busy January as the Latics fight relegation from the top-flight.