NASHVILLE, Tenn. — Prosecutors spent more than a week showing jurors photos and videos taken by Vanderbilt football players in a dorm-room sex assault. In response, the former players’ lawyers have sought to put the elite southern university on trial, blaming an anything-goes campus culture for warping the young men’s judgment.

Neuropsychologist James Walker testified Friday that wide receiver Cory Batey told him he had 14 to 22 alcoholic drinks before the players dragged the incapacitated woman into star recruit Brandon Vandenburg’s dorm room.

“Because he was this intoxicated, he was not his normal self,” Walker said. “He was doing things that he would not have done normally.”

Defense attorney Worrick Robinson sought to prove a point he made as the trial opened: that Batey had been an upstanding and promising young player before he “walked into a culture that changed the rest of his life.”

“Is there anything in their culture that might influence the way they act or the way they think or the way they make decisions?” Robinson asked his expert on psychology.

“Yes, at that age peer pressure is critical,” Walker responded, “because you’re just going out on your own, you’re not fully an adult, you’re not fully a child ... You tend to take on the behavior of people around you.”

Prosecutors repeatedly objected, and Walker ultimately acknowledged that he had done no scholarly work on Vanderbilt’s campus culture.

But even prosecutors presented testimony and evidence showing that before, during and after the attack on June 23, 2013, there were many people who failed to intervene. And the defense keyed on that, suggesting that the indifference of other students shows how common drunken sex was at Vanderbilt.

Cameras showed a crowd gathered around as Vandenburg pulled up in a vehicle in front of a dorm with his unconscious date. At least five students later became aware of the unconscious woman in obvious distress, but did nothing to stop it.

Rumors quickly spread around campus, and still no one apparently reported it.

The assault might have gone unnoticed and uncorroborated had the university not stumbled onto the closed-circuit TV images several days later in an unrelated attempt to learn who damaged a dormitory door. They were shocked to see players carrying an unconscious woman into an elevator and down a hallway, taking compromising pictures of her and then dragging her into the room.

Prompted by the video, school authorities quickly questioned the players involved, contacted police, who found a digital trail showing that one of the players was sending videos of it to friends as it was happening. The woman — a neuroscience student who had been dating Vandenburg before the alleged rape and returned to Nashville to testify — cried softly and the jurors stared wide-eyed as a detective narrated the videos Vandenburg shared and described the pictures taken on their cellphones.

She testified that she woke up in Vandenburg’s dorm room bed the next morning with her clothes on, and still has no memory of anything that happened after Vandenburg passed her drinks the night before, some of which were purchased for the players by a team booster.

Dillon van der Wal, who still plays tight end at Vanderbilt, testified that he didn’t tell anyone despite knowing the woman socially and seeing her unconscious in the hallway, with red hand marks on her buttocks.

“You thought well of her, you cared for her welfare,” defense attorney Fletcher Long said. “When you encountered her in the condition you found her with the marks you testified to, you called the police?”

“I did not,” van der Wal, replied.

“You called campus security?”

“I did not.”

“You reported it to the resident assistant?”

“I did not.”

“You reported it to your position coach?”

“I did not.”

“You reported it to the head football coach?”

“I did not.”

Vanderbilt officials have declined to discuss details of the case or their policies during the trial, but say school rules go beyond federal requirements for advising students how to respond to sexual violence. The university’s student handbook clearly lists resources available to victims and encourages anyone who witnesses possible sexual misconduct to take action and report it to law enforcement.

However, in response to questions from The Associated Press, Vanderbilt spokeswoman Princine Lewis said Friday that student rules are “meant to encourage reporting. It does not require it.”

Also charged with aggravated rape and aggravated sexual battery are Brandon Banks, who played defensive back, and Jaborian McKenzie, a receiver for the Commodores. All have pleaded not guilty. Banks and McKenzie will be tried later, and were not provided with plea agreements in exchange for their cooperation, prosecutors said.

No evidence or testimony was presented suggesting the woman was penetrated by Vandenburg. Others said he told them he was too high on cocaine at the time to manage that, even as the video shows him encouraging the others to violate the woman.

Jurors will have to decide whether that makes him criminally responsible. Closing arguments are expected on Monday.