Just days in, Bill Cosby's retrial is already packed with headline-grabbing variations from the court fight last year. But one of the prosecutors' more subtle strategy shifts could be the one that pays the greatest dividends.

Before parading a string of new accusers to the witness stand in Norristown — five former actresses, bartenders, or models who each told jurors the comedy icon drugged and assaulted them in the '80s — Montgomery County District Attorney Kevin Steele chose to kick off his case with a less emotionally charged but perhaps equally potent perspective from another, lesser-known woman.

Barbara Ziv, a forensic psychiatrist and Temple University professor, spent an hour on the witness stand Tuesday dispelling common cultural misconceptions on how sexual-assault victims ought to react to their abuse. It was a master class for understanding the #MeToo moment that has pervaded the wider culture since Cosby's last trial.

Critically, her testimony seemed designed to lay down a defensive perimeter and preemptively blunt the attacks Cosby's lawyers would lob at the accusers called to the stand throughout the week.

"Sexual assault is one of the most misunderstood crimes," Ziv told the jury of seven men and five women. "People think they know it. However, most common knowledge about sexual assault is wrong."

Victims rarely report their allegations immediately, she said. Some take years to acknowledge to themselves that they were raped. And once they speak out, the psychiatrist added, it is normal for victims' stories to evolve — even sharpen — over time, as they remember or accept more details of abuse they once tried to suppress.

"In 2018, I think that we are more educated about this as a society, certainly more than we were 20 years ago," she testified. "But it is still part of the U.S. rape myth that we blame victims for not being the kind of victims that we think that they should be."

Ziv's impact on the jury remains to be seen – Cosby's lawyers are expected to only step up their attacks as the central accuser, Andrea Constand, returns to the witness stand Monday.

But in cross-examination, defense lawyer Kathleen Bliss strove to deflate the psychiatrist's testimony and invited jurors to question whether her broad-brush conclusions applied to any of the specific six accusers that prosecutors would call to testify.

"Allegations of sexual assault can be made by a true victim, just as they can be made by a liar, can they not?" Bliss asked — a point Ziv conceded.

Still, her dispelling Tuesday of what she repeatedly described as "rape myths" at the start of the trial foreshadowed much of the testimony in the ensuing days.

"One of the consequences of sexual assault is that it makes you doubt yourself and judgment of the world," Ziv said. "You hold out hope that there is some logical way that you can wrap your mind around what happened in a way that doesn't mandate that you throw out your belief in your own judgment and your belief in that person."

That sentiment hung over the courtroom a day later as Cosby accuser Janice Baker-Kinney described her own struggle to finally use the words sexual assault to describe her alleged encounter with Cosby in 1982. Baker-Kinney insisted that for years she had blamed herself for making "a stupid choice" — accepting Quaaludes from the comedian at a Reno, Nev., get-together that later caused her to black out.

"It still takes me everything in my being to say the words  I was raped, because I still carry the guilt," Baker-Kinney said. "Back then, there was no 'acquaintance rape' or 'date rape' or anything like that. I didn't have the verbiage."

Defense lawyer Tom Mesereau scoffed at the idea that it had taken three decades for Baker-Kinney to conclude that she had been raped – and only after other women began coming forward to accuse Cosby.

On Friday, when the defense aimed its attack on Constand — who says Cosby drugged and assaulted her at his Cheltenham home in 2004 — about the shifting accounts she gave to police over several interviews more than a decade ago, Ziv's words again echoed.

"People believe a victim of sexual assault should be able to tell you a consistent, coherent narrative of what happened," the psychiatrist had testified. "In my experience, I don't think I've ever seen that pattern of reporting from a victim. People's memories may be impacted by substances, but they are also impacted by the sexual assault itself."

Feelings of disassociation, out-of-body experiences, and focusing on seemingly odd, extraneous details are also routine, Ziv had told jurors.

That testimony resonated when accuser Heidi Thomas testified about keeping mementos and photos from her 1984 trip to Reno, where she says her assault by Cosby occurred.

"Nowadays, I look back and think, 'You really saved the boarding pass and a jacket from the plane ticket?' " Thomas said, surprising herself with her behavior. "But yeah, I guess I really did."

Prosecutors had also offered testimony at the first trial from a sex-assault expert designed to serve much the same purpose. But the timing was markedly different.

That witness, Veronique Valliere, testified in the waning days of the trial  – and well after the defense had spent hours attempting to discredit the testimony of Constand and Kelley Johnson, a former talent agency assistant who was the only other Cosby accuser then permitted to testify.

Cosby's defense lawyers at that time accused Valliere of trying to patch over earlier testimony with her broad-brush descriptions of victims' post-assault behavior and accused her of having a rooting interest in the case — pointing to Facebook posts in which she seemed to cheer on the Cosby prosecution.  

As a result, Valliere had less impact as a witness than she could have, said Dennis McAndrews, a former prosecutor who sat through last year's trial and attended the proceedings last week.

"It was less effective coming late in the trial," he said. "It was particularly critical to do it up front [this time] because of the number and nature of the accusers. It was important for the jury to hear right away why each of the accusers would not have had a prompt outcry especially with someone with the power, money, fame, and prestige of Bill Cosby."

The decision to let Ziv testify could face its biggest test Monday. That's when Constand returns to the witness stand for what's expected to be an intense cross-examination.

Keep up with every development in Bill Cosby's case with our day-by-day recapstimeline, and explainer on everything you need to know about the case and its major players.