Columbia University President Lee Bollinger didn't shake hands at graduation with Emma Sulkowicz, who carried a mattress across the stage as part of her senior thesis and ongoing protest against her rape.

Bollinger appears to turn back to toss a plastic bottle onto his chair just as Sulkowicz and her friends approach him.

The handshake is standard at most academic ceremonies, and Bollinger can be seen shaking other students' hands after Sulkowicz and her friends passed.

"I even tried to smile at him or look him in the eye, and he completely turned away," she told the New York Times. "So that was surprising, because I thought he was supposed to shake all of our hands."

A spokesperson for the university told BuzzFeed News that the article "reflects a highly selective and strained interpretation of actual events," and that Sulkowicz and the students who walked the stage with her "marched right past Dean Valentini and President Bollinger rather than pausing for traditional handshakes."

The spokesperson acknowledged that that is the students' right, but that anybody who knew the university president personally would know that the snub was unintended.