General Motors Co. will create “a new norm and a new industry standard” for safety and quality, the automaker’s chief executive officer, Mary Barra, said Wednesday in her first public appearance on Capitol Hill since the publication of a critical report of the company’s handling of an ignition-switch defect.

Appearing with former U.S. attorney Anton Valukas, the Jenner & Block chairman who wrote the report, Barra tried to convince skeptical House panel members that GM’s efforts to address the findings is “more than a campaign” and is intended to change the way company employees think and act.