Jessica Mayer talks in terms of ‘us’ and ‘we’. We want to share with you. We’d like to show you.

She’s not referring to her husband or her children. She’s referring to the “family in her mind”.

She has Dissociative Identity Disorder (DID) and is hoping to dismantle some of the stigma around mental illness and the fear and judgment and uncertainty typically triggered by the misused phrase ‘split personalities’.

She is Jess, 25, from Windsor in the UK.

She is also Ollie, a 14-year-old student in the same town. “He wants to grow up and be a dinosaur,” she told Channel Seven’s Sunday Night.

She is Jamie, a doctor with a “posh accent” who is “intelligent and charming”. He’s 27.

There is Eddie, a 29-year-old punk-rock hairdresser. “He’s very artsy, very creative.”

And finally Jake, a 25-year-old Californian pop-star who ‘lives’ in Hollywood. “Jake is about five-foot six and he’s very slim and lean and muscular. He’s got this American white smile and he’s very good looking,” she said.

The personalities – or ‘Alters’ as Mayer calls them – interact in her mind “like a family”. It’s her own inner world where Jamie and Jake are brothers; Eddie and Jamie are partners; and Ollie is their son.

There is an outer world, too. Mayer and her husband have been together for 10 years. He says “more the merrier”, referring to her various personalities, and maintains a bisexual relationship with both Jess and Eddie.

“Forget about the axe murderer around the corner,” Mayer said, referencing the way ‘split personalities’ can be portrayed in pop culture. “Nobody is going to hurt you.”

Jess started to display some of the signs of a switch during our interview. #SN7 pic.twitter.com/2wgLqe7G8j

— sunday night (@sundaynighton7) September 10, 2017

According to the National Alliance on Mental Illness in the US, the condition affects around two per cent of people, with females more likely to be diagnosed than males.

Though causes are difficult to pin down, it seems to stem mainly from childhood trauma – not substance abuse, as often claimed. Psychology Today states 90 per cent of suffers in the US, UK and Europe report experiencing childhood abuse.

Mayer herself suffered a traumatic childhood and, though she didn’t provide details, she said simply: “What happened to me would not have happened if I was a boy”. It’s this fact, she believes, that led to four of her ‘alters’ being male.

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“When a child experiences trauma, parts of their consciousness actually break apart,” Mayer had previously explained in a YouTube video Meet the alters. “When you can’t ‘fight’ and you can’t ‘flight’, the brain can detach and that detached state can turn into alters.”

“Alters can be stuck at a certain age. They can be a different gender, animal alters, inanimate objects. Over time, they form three-dimensional personalities. They have their own experiences and become their own person.”

Mayer wants to change the narrative. She wants to raise awareness around a condition that’s often misunderstood as something to be feared.

Though self-harm can sometimes be attached to certain ‘alters’, the condition doesn’t automatically attach itself to violence.

“Alters are very unlikely to harm you, and as with most mental health issues, sufferers are more likely to be victims than perpetrator,” she said.