When a person reports a sexual assault to the police and previously knew their attacker, the ability to prosecute or not often comes down to consent.

The public’s understanding of consent has changed in recent years to better reflect reality, but there are many people who cling to outdated and erroneous assumptions, experts say.

“Consent is freely given, meaning someone chooses to say yes to something because they want to, not because they’re pressured, manipulated or threatened,” said Mallory Michel, prevention coordinator with Pennsylvania Coalition to Promote Respect. “People are free to say ‘yes’ or ‘no’ without fear of negative consequences.”

Consent is only valid if a person is of sound mind, sober and of legal age, she said. And consent is reversible, Michel said, meaning anyone can change their mind at any time.

“Just because someone agrees with one thing doesn’t mean they agree with everything or can’t change their mind, even in the middle of an activity,” she said.

If you have to wonder if the other person wants to be touched, they probably won’t, victim advocates say.

“Silence or not saying no is not the same as giving consent. Neither lack of resistance nor clothing defines consent,” said Amnesty International, an international human rights organization. “And consent doesn’t mean signing a contract – it doesn’t have to be expressed in words – it has to be explicit and enthusiastic.

“If someone doesn’t agree to have sex, it’s rape. It’s as simple as that.”

There are at least five myths when it comes to proper sexual consent Healing Abuse Working for Change, a national domestic violence organization.

One of the most common is the belief that consent is only required once, compared to each specific sexual activity, HAWC said.

“No matter what a person wears, how they flirt, or whether they’ve initiated sexual activity, you can’t assume that he or she is asking for anything other than exactly what they’re comfortable with at the moment,” HAWC said. “Similarly, if you’ve had sex with someone in the past, you can’t assume that person consents to having sex now.”

David Wahl, a sociologist who has studied sexual violence for nearly a decade, said he has seen an increase in the use of sexual gas in recent years.

Gaslighting involves an abuser manipulating a victim into questioning the reality of a sexual encounter.

A woman who repeatedly told her husband she was not interested in anal sex said her husband began regularly plying her with alcohol until she became nearly unconscious, Wahl said. Afterward, she told Wahl she didn’t remember anything, but she knew a sexual encounter had taken place.

“You told me you wanted to, that’s why I did it,” her husband told her.

One night, the woman pretended to drink alcohol so she could catch her husband sexually assaulting her when she thought she had passed out, Wahl said.

Although gaslighting has become commonplace, Wahl said, most of the victims he interviews are unaware they’ve been manipulated. Because of that, most of them don’t realize they’ve been bullied and never report it, he said.

Wahl said women rationalize unwanted sexual encounters with thoughts such as, “If only I had done that, he wouldn’t be upset” or “I can change him. He’s just going through a tough time.”

While meeting with groups of male student-athletes on college campuses, the national advocacy organization It’s on us presents hypothetical scenarios and asks men to consider whether consent was given in each case.

Executive director Tracy Vitchers said the organization saw a clear difference between white and black men when it came to their threshold of consent or not. Black men generally say they want a clear, verbal “yes” to sex, while white men are willing to agree to nod, touch or “lean into sex,” Vitchers said.

It’s On Us also happens with men when consent can never be given: when a woman is asleep, for example, or when someone is under the influence of drugs or alcohol.

“Those gray area excuses are not acceptable,” Vitchers said. “We always tell the students we work with, ‘If you’re not sure, it’s a no.'”