If the 25-year-old is found competent, he could be sentenced to up to two years in state prison.
The actress did not appear in court. She has previously testified in a civil restraining order hearing that she feared Loring, who police say repeatedly went to the starlet's home and left her numerous items, including some disturbing drawings.
Loring is due back in court on Sept. 20 for sentencing.
The Associated Press contributed to this report.