Britney Spears "turned up the performance" in front of her family on set.

The 30-year-old pop songstress is mother to children Sean, 6, and Jayden, 5.

Britney's fianc Jason Trawick and the kids visited her while she was filming a TV advert for Hasbrow's new game Twister Dance recently.

Director Ray Kay noticed that the singer was palpably invigorated by her family's company.

"The shoot went really smooth. Britney always delivers, and we had a good time on set," Ray told Us Weekly. "She brought Jason Trawick and the boys to set, and it was really great to see how her performance was stellar when the boys were watching the monitor. It's like she turned up the performance one notch more."

Ray has worked with Britney before on her music video for single Till the World Ends, which won a trophy for Best Pop Video at the 2011 MTV Video Music Awards.

The director is impressed by Britney's versatility.

"I think the reason Britney's been able to stay on top for such a long while is that she's renewed herself, trying out different kinds of music and expressions throughout the years," Ray said. "She's simply an interesting character."