It's one of the most tired tropes in TV Land. A character gets bumped on the head or falls down the stairs and suddenly has amnesia. He can't recall who he is or what he used to do, which results in a new set of complications, often played for laughs. Just before the end of the episode, he gets his memory back thanks to — you guessed it — another blow to the head.
It's so ingrained in our minds it's no wonder between 38 and 46 percent of Americans think amnesia can be cured by a second blow to the head. And this TV trope didn't come out of thin air. It was a plot device in numerous novels of the 19th century and believed by many doctors of the period.
In her 2016 article, "The Head Trauma Amnesia Cure: The Making of a Medical Myth" published in the journal Neurology, Drexel University associate psychology professor Mary Spiers looked at where this belief originated. In the late 1700s and early 1800s, she wrote, scientists thought that the two halves of the brain had the exact same function, much as the body has two eyes. French anatomist and physiologist Francois Xavier Bichat proposed that a second blow to the head could restore the memory of someone who had a concussion. His reasoning was that the two hemispheres of the brain needed to be in balance with each other to function. So, if an injury to one hemisphere could cause confusion to the other hemisphere, a second blow should make everything right again.
"From my reading of Bichat's work, it seems that he felt that the second trauma amnesia cure was a common occurrence and didn't need the citation of an individual case," Spiers said in a press release. "This was not unusual at the time, to forgo evidence like that."
Ironically, Bichat died of a head injury in 1802. But his theories lived on, and other doctors expanded on them. A physician named Andrew Wigan wrote in an 1844 book of a case where a 16-year-old boy rendered "insensible" by a blow to the head suddenly came out of a coma weeks later after the clatter from someone accidentally dropping fire tongs awoke him.
Meanwhile a second idea also was taking hold — that of memory permanence. Philosopher William James credited poet Samuel Taylor Coleridge with the notion that memories are forever etched in the brain, Spiers wrote. Coleridge used a well-known story of a woman whose "ravings" turned out to be forgotten memories, to make his point. Although Coleridge was no scientist, he lived in a time when there were no "hard and fast lines between scientific and popular writing," wrote Spiers. These ideas about amnesia have persisted long after Coleridge, Bichat and Wigan and become part of literature, movies and TV.
By the mid-1800s, scientists were beginning to question these beliefs about amnesia. Today we know that amnesia is caused by stroke, brain inflammation from an infection, a brain disease (like Alzheimer's), seizures or tumors. Blows to the head (concussions) cause confusion but very rarely result in permanent loss of memory. Even among amnesia patients, it is far more likely that they lose the ability to make new memories, than that they completely forget who they are. There isn't any treatment for most types of amnesia. Patients instead are taught coping skills (like using smartphones to keep track of daily tasks). And, no, a second blow to the head won't fix the problem.
"One of the issues we see in the persistence of this myth is that understanding how the brain forgets, recovers and/or loses information is a complicated matter that is still being studied by brain scientists," Spiers said. "As individuals, we may have had the experience of a 'memory jog' or cue that reminds us of a long-forgotten memory. Because our own experiences serve as powerful evidence to us, this reinforces the myth that all memories are forever stored in the brain and only need some sort of jolt to come back."