Anomalisa, an animated film, centres around the Fregoli syndrome, a rare disorder in which someone believes all people are, in their reality, a single person with a common appearance. Michael, the lead puppet character, is a stereotypical pot bellied middle-aged British author (voiced by David Thewlis) who lands in Cincinnati to deliver a conference keynote speech on Customer Services.

For him, everyone - from his wife, to his son, to his taxi driver and hotel concierge, all except Lisa, a Customer Services Team Leader and conference delegate - shares an identical face and an identical male voice regardless of gender. To survive, Michael fixates on Lisa because she has a 'Miraculous voice.' He calls her an anomaly, which she is, in his distorted perception as she is different from the same-faced ones. She is his Anoma-Lisa, and ultimately the only being he can cling to when his nightmare eventually goes viral in a stylised sequence where face-same people pursue him carnally, emotionally, physically - all saying they love him. A terrifying experience, even for a puppet.

We may all have experienced similar illogical paranoid angst to some extent in the past, for who has not suddenly wondered who we are, who everyone else is and why we don't fit in? Or felt that we are truly alone when with friends and family, worried that no-one understands what is going on in our heads or that we simply don't exist - that people act as if we were disembodied? Such feelings of dislocation and isolation are common and stem from a well recognised primal fear of non existence.

For Jung it took the form of The Nekyia or Night Sea Journey as he lost interest in his work, gave up his job and withdrew from the world to explore his own urgent unconsciousness. Douglas Adams described the experience more graphically in The Long Dark Teatime of the Soul: 'For a moment (he) had a sense of infinite loss and sadness that somewhere among the frenzy of information noise that daily rattled the lives of men he thought he might have heard a few notes that denoted the movements of gods.' And the Fregoli syndrome is similar to the Capgras delusion, where familiar people are replaced by imposters – a condition made famous by The Invasion of the Bodysnatchers.

Only around 40 cases of Fregoli – which incidentally is the name of the hotel where Michael experiences his very strange few days - have been reported worldwide, with studies at one clinic estimating the delusion is present in 0.2% of psychiatric patients and 0.5% of patients with dementia. In one recent case a 21-year-old male patient who’d fallen in love, but been rejected by a girl, became convinced that all his Facebook friends were that same girl, using a facial cream to disguise herself. He was therefore convinced that – whatever she maintained - the girl was still interested in him.

Distancing the audience using face-same puppets is a deliberate technique used by Director Kaufman to give us the experience of Fregoli: "I started thinking about that in a metaphorical way, not what does it mean literally to have that condition, but what does it mean to not be able to connect and see other people, and how does our society create or contribute to that feeling or that inability that we might have or one might have."

This would have been very difficult using actual actors, for obvious reasons. And given the slow script, the emphasis on pedantic detail which grinds you through the excruciating minutiae of Michael's boring life as he lumbers along trying to cope with his delusions, it would not have been at all a compelling film with real actors.

As it is, we are distracted from the mundanity by marvelling at the intensely human way these puppets move; their facial expressions, utterly convincing body language, thinking, 'How did they do that?' Anomalisa is therefore an animation which challenges us on many levels of unreality, not only of seeing and believing.

Through it, Kaufman exposes our world where everyone feels peer pressure to look the same, modelling their appearance on media images of perfection, changing it regularly to emulate what is currently fashionable with make-up, surgery, designer brands and our behaviour, so those we see and in turn become, are more sexlessly indistinguishable and androgynous.

Taken to its logical conclusion the joints in the puppets' face plates in Anomalisa, the hairline crack, the split between the eyes and the lower face echo attempts to engineer our collective ideal identical images. Frighteningly though, when Michael undergoes the nightmare of extreme dissociation half his face drops off revealing grey nothing underneath. What price is any self worth bound up in appearance then?

Finally, Anomalisa is a direct challenge to the idea that animated films are only for children. Not so. This one contains flabby nudity, explicit sex, a dancing animated vibrator which has to be seen to be believed, a mechanical Japanese sex toy with half a breast and the F-word is splattered wantonly throughout. And of course, none of it is what it seems….. You have been warned!

Book your ticket to see Anomalisa at FACT here.