Head injuries won't necessarily turn Jekyll into Hyde

I already shared this on my social media feed, but it turned out to be rather long. And I find it so interesting I want to keep it here as well as a go-to reference. This version has some very minor editing and additions. It's a lot more "quotes from the article" and a lot less of my own commentary than usual, but if you're already familiar with Phineas Gage, it'll save you a long read on Aeon (if you're not, I suggest you just use the link immediately below instead).

This is an absolute belter of piece from Aeon ! I haven't kept up with them much of late (there's just not enough time) but I immediately went to the site and downloaded a few more articles to get back into the swing of things. Aeon do have the occasional utter dud on an article, but when they're right, they're right.

You've probably heard of Phineas Gage, the 19th century railway worker who survived a horrific brain injury only to come out with a changed, ill-mannered personality. Well, he did survive, but the evidence for a changed personality is next to non-existent.

There are three primary sources written about Gage by people who met him. Harlow wrote his first report in 1848, limited to an account of the recovery, and a second in 1868, which reproduced the first and added further interpretations. Another physician, Henry Bigelow, wrote a paper after meeting Gage the year following the accident. 

Of the two, only Harlow mentions Gage’s personality change. His total word count on the subject is just over 300. [My emphasis] At no point does he ask Gage about it or offer any quotes from him – Gage was dead by the time Harlow wrote the second paper. Nothing written by anyone who knew Gage before his injury survives, only paraphrases noted down by the two doctors. 

So, the sources are scant to begin with. And, according to the psychologist and historian Malcolm Macmillan in 2008, most of those who have written about Gage since the primary sources were published do not appear to have checked them, promoting some aspects of the story, ignoring others and embellishing liberally. Macmillan’s conclusions were echoed in a separate 2022 review of more recent Gage literature, which found that half of the 25 papers analysed gave negative descriptions of Gage that were not based on the primary sources.

It really is quite concerning how often widely known stories turn out to be based on almost nothing. The unfortunate part is that because everyone repeats it, it's easy to assume that this is because it's well-verified. But this, unless the reports are all independent, is circular : more repetition sounds like ever-greater credibility, even when it's just literally repeating what someone else said. Now a lot of independent verifications do constitute powerful evidence, to be sure, but a lot of people repeating the result does not. The difficulty is that the brain doesn't instinctively understand this.

Hanna Damasio’s claim that Gage ‘began a new life of wandering’ seems to be extrapolated from a single use of the word ‘wanderings’ by Harlow, in context of the difficulty he had in tracking down Gage in later life. Nowhere did Harlow or Bigelow suggest that ‘wandering’ was typical of Gage’s post-injury existence.

Of the various falsehoods written about Gage, perhaps the one most clearly contradicted by the primary sources is the Damasios’ claim that Gage ‘could not be trusted to honour his commitments’ and that he ‘never returned to a fully independent existence’. In fact, the sources make no mention of Gage being dependent on anyone from the time he recovered from the injury until the last year of his life when he succumbed to illness. They also clearly state that, after he gave up his public appearances, he worked at a livery stable for 18 months and then he moved to Valparaíso in Chile where, according to Harlow, he worked for nearly eight years, ‘caring for horses, and often driving a coach heavily laden and drawn by six horses’.

As Macmillan pointed out, the available facts about Gage fly in the face of claims made about his transformation and reduced capacities. Macmillan gave a carefully sourced description of the demanding nature of Gage’s job in Chile: the dependability required of him in rising in the small hours, loading passengers’ luggage and possibly handling fares; the high level of dexterity and sustained attention necessary for driving six horses; the foresight and self-control involved in navigating the unwieldy coach along the crowded and sometimes treacherous Valparaíso-Santiago road. He also pointed out that Gage, at first a stranger to Chile, would have had to learn something of its language and customs and ‘deal with political upheavals that frequently spilled into everyday life’.

So really, little or no credible evidence for his supposed changed personality from mild-mannered worker to whoremongering brute. It just didn't happen. He became an expat working in the hospitality industry, for all intents and purposes.

The other case is of Eadweard Muybridge, the photographer famous for those early time series photographs of running horses and the like. I'm never heard that there was a claim he had a changed personality, even though he did something much worse than Gage after surviving a stagecoach accident :

...he discovered that his wife, Flora, had become romantically involved with a local theatre critic and, by one biographer’s description, ‘swindler’ called Harry Larkyns. Soon after that, Muybridge came to suspect that his infant son was in fact Larkyns’s child. Muybridge travelled to the town of Calistoga, 75 miles north of his home in San Francisco, and knocked on Larkyns’s door. When Larkyns appeared, Muybridge shot him in the chest with a pistol. Larkyns died at the scene. Muybridge did not resist arrest, freely admitting to the murder, and was held in custody until his trial the following February.

If the testimonies of his friends are to be believed, it was the instability brought on by the brain injury that led Muybridge to kill Larkyns. ‘The killing would have surprised me much before his accident but not much after it,’ said one defence witness, according to the Sacramento Daily Union. The brain scientists take it at face value – labelling the murder as Exhibit A in their argument for Muybridge’s disinhibition.

Why, then, don’t we find Muybridge alongside Gage in neuropsychology textbooks or Wikipedia articles about frontal lobe function? The simplest answer is that neither the testimonies about his personality change nor the retrospective assessments of the clinicians are believable. Some of them amount to very little even on paper – the mention by his friends of Muybridge’s hair changing colour and his idiosyncratic approach to business, for example. But, more pressingly, the testimonies were given in support of an insanity plea submitted by Muybridge’s defence council, in the hope of saving him from the death penalty. How sure can we be that his friends would have said the same things without the urgent stakes of the trial hovering in their minds?

Even if we accept the testimonies as the whole truth, it’s notable that the jury present at the trial roundly rejected the insanity plea. In violation of the law and of the judge’s instructions, when they acquitted Muybridge, it was on the grounds that Larkyns’s death was not a murder committed by a mad person but a justifiable homicide committed by a sane one. Perhaps they’d read the interview with Muybridge published by the San Francisco Chronicle while he was in prison awaiting trial. He is quoted as saying:

"I objected to the plea of insanity because I thought a man to be crazy must not know what he was doing, and I knew what I was doing. I was beside myself with rage and indignation, and resolved to avenge my dishonour.I objected to the plea of insanity because I thought a man to be crazy must not know what he was doing, and I knew what I was doing. I was beside myself with rage and indignation, and resolved to avenge my dishonour."

Fortunately for him, his photography had made him famous. And so the results were quite different from Gage, who was blamed for doing nothing, whereas Gage was excused murder :

The forces of social status and uncritical trust in professionals that worked so well in Muybridge’s favour did the opposite for Gage. During his life, he may well have had friends. People were willing to employ him. He was cared for by his family towards the end. And there’s no suggestion in the primary sources that he ever became isolated or spurned from any community. However, without powerful or wealthy friends to defend his reputation, the story told about Gage by Harlow operated in isolation after his death. In the absence of dissenting voices, it was treated as fair game by commentators with their own professional agendas.

Finally, the main point of the essay is against the notion of "disinhibition", or at least that this shouldn't be used as an easy explanation for all psychological changes or disorders :

Among those who have accepted the revision of the Gage story, the consensus seems to be that his character probably did change but that any disinhibition that did occur was temporary. But it’s important we subject even this claim to counter-proposals, that we ask what else might have provoked such a temporary change, assuming we believe in it. Some have suggested that psychological trauma might have played a role... But maybe Gage was just pissed off.

On a modern case :

Callum was clear that both examples were out of character but that they still held meaning. ‘In the first instance, even though my family were a bit surprised at what I was saying, it also reassured them that I was still the same person. I was suggesting doing things that demonstrated I remembered my friends, even if my family didn’t want to hear about those things.’

This persistence of self was something Callum also emphasised about the apparent disinhibition. Disobeying doctors’ orders by wheeling himself out of the hospital may have been atypical for his pre-injury character, but this behaviour still belonged to him rather than to some mysterious new identity ‘unveiled’ by the injury. ‘I’m not a different person,’ he said. ‘I’m me after something traumatic has happened to my brain. It was still me doing those things. It was me who was disinhibited.’ And he also insisted that the behaviour held value.

Personalities vary all the time. The difficulty, I guess, is in deciding when a change is legitimate or valid. One person can be excused murder because they lost their temper; another can become a textbook classic because maybe they felt a bit grumpy one morning after taking a bolt to the head. As Cicero said (In Defence Of Milo) :

If our lives are endangered by plots or violence or armed robbers or enemies, any and every method of protecting ourselves is morally right. When weapons reduce them to silence, the laws no longer expect one to await their pronouncement. For people who decide to wait for these will have to wait for justice, too – and meanwhile they will suffer injustice first.  

And motivation does matter. But Cicero was explicitly referring to self-defence, not premeditated murder (though he had no qualms about this when it came to tyrants and the like : "to end the life of a man who is a bandit and a brigand can never be a sin"). 

Yet when someone respected does something abhorrent, we're all too apt to assume they must have had a good, valid excuse and it doesn't represent their true character. When someone of lowlier standing does something considerably less problematic, we assume that they must have had some horrible psychological problem; we view their character and agency as somehow less valid than that of others – even their trauma must reflect some deep flaw rather than their making a real choice. The tale grows in the telling indeed.