Both lead to mental or neurologic symptoms without any identifiable cause.
The difference is that while malingering is conscious and willful, conversion disorder is subconscious and involuntary.
What does this mean?
Well, malingering is deliberately feigning or exaggerating physical or mental symptoms motivated by a desire for financial compensation or avoiding work or military service:
One famous TV example of malingering was George Costanza, who faked a disability to get access to the executive bathroom:
Another example, one of my personal favorites, is taken from Dirty Rotten Scoundrels.
Steve Martin, faking a disability to con money out of Glenne Headly, is tormented by competing con man Michael Cane who is pretending to be a doctor:
In conversion disorder, or hysteria, the mental or physical symptom develops subconsciously in response to some stressful event or situation, and the affected patient truly believes they have a physical problem.
The Freudian theory suggests that a painful experiences is consciously repressed as a way of managing the pain, but this emotional charge is somehow “converted” into the neurological symptoms.
In this scene from Talladego Nights, Ricky Bobby (Will Ferrell) emotionally traumatized by an accident, believes he is paralyzed.
In this (long) clip taken from Speed Racer, Speed challenges a washed up racer to “wake up” his paralyzed R arm and race again:
Finally, there many cases of both malingering and conversion disorder brought on by the stress of war in active duty military, and this recently declassified WW2 documentary from 1946 “Let there be light” shows examples of “Shell Shocked” G.I.s undergoing some unconventional treatments.
Mass hysteria is a particularly interesting social phenomenon where many people in one group together all share the same collective delusion of a disease, fear or exposure:
Perhaps the most recent example of mass hysteria occurred in LeRoy New York in 2011-2012. The 12 high school girls all developed Tourette-like symptoms , which led to extensive testing of their school for toxins. The were all ultimately diagnosed with mass hysteria and conversion disorder:
So, is there any concrete way to differentiate malingering from conversion disorder?
The answer is, maybe.
There are many clues gleaned from the physical exam that suggest a patient’s findings are non-organic, but this won’t tell you if the process is volitional or subconscious.
In a recent study, investigators compared PET scans from healthy individuals instructed to feign left arm weakness operating a joy stick, compared to controls who did the movement tasks normally.
The feigners both had abnormal hypofunction of the right anterior prefrontal cortex not seen in the controls.
Perhaps a future objective test for malingering?