You’re probably familiar with the TV or movie plot device where a character is conked on the head, loses memory or identity and then gets conked again and memory is restored. Classic examples are in the 1951 Tom and Jerry Cartoon Nit-Witty Kitty and the movie “Clean Slate.”

This “double-conk” myth is so far off from neurological fact that it is laughable to scientists and physicians. It’s never a good idea to hit someone on the head as a cure for any type of concussion or brain injury. Yet surveys of the public find that around 40 percent believe that a second blow to the head can help someone recover forgotten memories.

I’m a clinical neuropsychologist and I study memory and memory disorders. In the classroom, I use movies to demonstrate how brain science and neuro-myths are depicted in popular film. Amnesia is a popular theme. In fact, there have been more amnesia movies made than for any other type of neurological disorder and many of them depict the myth of the “double-conk.”

So I wanted to find where this idea first came from. Did it just emerge from the mind of a creative Hollywood writer or filmmaker? I was surprised to find the origins of this particular myth go back to the early 19th century.

Back to the early 19th century

I went through troves of old movies and books, tracing the myth back to the silent movies of the early 20th century and late 19th-century fiction, including novels published in serialized form in newspapers.

In my research I also uncovered what I would call “pop psychology” newspaper stories about memory, many of which are wildly inaccurate, but reflected what was being written for the public. Then I tried to align the emergence of the double-conk story theme with both scientific and popular writings about brain and memory functioning from the 19th century.

To my surprise, I found what I believe may be the first “scientific” endorsement of a “double-conk” cure in the writings of French physician Francois Xavier Bichat, published after his death in 1802.

Bichat was a young up-and-coming anatomist who believed that the two brain hemispheres were identical in structure and function. In a healthy brain, he reasoned, the hemispheres are in balance with each other and therefore in symmetry. Therefore, if a person is hit on one side of the head, the brain can lose balance, causing confusion or mental derangement.

The cure, in Bichat’s opinion, was a blow to other side. He wrote that “observations so frequently repeated of an accidental blow upon one side of the head having restored the intellectual functions, which had long remained dormant in consequence of a blow received upon the other side.”

My suspicion is that Bichat’s endorsement of a double-conk cure is based on folklore idea because he doesn’t cite or explain any individual cases to support his claim, while implying that a second blow restoring function is a common occurrence. He then uses this example, without question, to support his ideas of brain symmetry and balance.