Joaquin Phoenix did some impressive research, in order to get into character as the Joker.

The actor stars as the iconic villain in the upcoming film “Joker”, which will have its North American premiere at next month’s Toronto International Film Festival.

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The 44-year-old spoke with Italian newsmagazine Il Venerdí about inhabiting the role.

“I saw videos showing people suffering from pathological laughter, a mental illness that makes mimicry uncontrollable,” Phoenix revealed, as translated by NME.

The rare disorder can cause sufferers to laugh or cry uncontrollably, and it is sometimes linked to people with Parkinson’s or multiple sclerosis or those who have endured traumatic brain injuries or strokes.

RELATED: Jared Leto Says He ‘Would Definitely’ Play The Joker Again

Phoenix is hardly the first actor to go deep to play the Joker. For the character’s previous incarnation in “Suicide Squad”, actor Jared Leto was reported to have played twisted pranks on co-stars involving animal carcasses and more.

Fans can see Phoenix’s medically informed take on the character when “Joker” hits theatres October 4.