Demi Lovato says is the toughest judge on "The X Factor"

Singer says he does not understand the decisions of fellow

Demi Lovato revealed that sometimes Britney Spears asks "what she was thinking" when they vote in favor of some of the singers of "The X Factor" American.

The two singers will be, along with Simon Cowell and LA Reid, the judging panel of the series and Demi says it is impossible to predict what the other jurors think:

"It's unpredictable. Sometimes I can not see what Simon saw in a candidate. And the same goes for Britney, I ask myself, 'Britney, what are you thinking?'" Said the singer.

The singer of "La La Land" continued: "For the most part, I agree with Britney, more than Simon. Perhaps because we are the only girls in the program."

Demi also revealed that likes to offer constructive criticism to the candidates of the program: "I am very honest in the program and sometimes seem to be harder to judge. You can say that I always speak my mind"