Justin Bieber arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

Carly Rae Jepsen performs at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Matt Sayles/Invision/AP)

Ke$ha performs at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Matt Sayles/Invision/AP)

Taylor Swift accepts the award for favorite female artist - country at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by John Shearer/Invision/AP)

Nicki Minaj accepts the award for favorite album - rap/hip-hop for "Pink Friday: Roman Reloaded" at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by John Shearer/Invision/AP)

Usher performs at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by John Shearer/Invision/AP)

Christina Aguilera arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

Kelly Rowland arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

Ryan Seacrest presents the award for favorite male artist - pop/rock at the 40th Annual American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Matt Sayles/Invision/AP)

Musical group No Doubt, from left, Adrian Young, Gwen Stefani, Tony Kanal and Tom Dumont arrive at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

PSY arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

Ke$ha arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

Hayden Panettiere arrives at the 40th Anniversary American Music Awards on Sunday, Nov. 18, 2012, in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

LOS ANGELES, CA - NOVEMBER 18: Singer Justin Bieber accepts the Favorite Pop/Rock Male Artist award onstage during the 40th American Music Awards held at Nokia Theatre L.A. Live on November 18, 2012 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)