I can spend a ridiculous amount of time discussing an adventurer through space and time known as the Doctor, the eponymous and millennia-old hero of the BBC's 50-year-old television program Doctor Who. Catch me tweeting on a night when I'm in the mode to contemplate the nature of the Doctor's personality and regenerations, and you'd be best be ready to see a veritable barrage of Whovian analyses fill your Twitter screen.
Known by no other name, the Doctor travels through the universe and its history in his stolen time machine, the TARDIS, usually accompanied by an attractive Earth girl although there have also been a few blokes, some non-humans, and a robot dog along the way. In 1966, three years into the show's early run, producers recast the role. Out went actor William Hartnell, whose version would become retroactively known as the First Doctor, and in came actor Patrick Troughton (who looked nearly nothing like Hartnell) as the Second Doctor. To account for this drastic change, the showrunners introduced regeneration, originally known as renewal. This process would let them replace their leading man periodically over the next half century, leading up to this week's first full episode starring Peter Capaldi as the newly regenerated Time Lord, known to us as Twelfth Doctor.
On the verge of death, a Time Lord such as the Doctor might heal through a glowing, spectacular process that changes every cell of his or her body (perhaps even changing him into a her, a possibility that has been mentioned although we've yet to see any Time Lord change so on screen). Altering everything, including his brain, produces alterations in personality and deficits in memory. We know that changes to a human brain can alter personality and impede memory functions in a variety of ways. At least temporarily, while the regenerated body adjusts over the course of hours, the Doctor tends to show varying degrees of delirium with confusion, erratic actions, and deficits in memory and attention.
In that particular conversation, we mainly discussed the psychology of Time Lord regeneration.
Dr. Travis Langley, a professor of psychology at Henderson State University, is also an avid Doctor Who fan and author of Batman and Psychology: A Dark and Stormy Knight. When we discussed the Second Doctor’s initial identity confusion, Dr. Langley said, “We know from ‘The Three Doctors’ that Hartnell’s Doctor is the first one; he didn’t have previous versions of himself we didn’t see. So when the Second Doctor arrives, this is someone who’s just experienced regeneration for the first time and wasn’t really expecting it that day. It makes sense that, at least at first, he feels disconnected from his old self. People who’ve had serious facial reconstructive surgery can experience a depersonalization effect. When people change their names, it can take a while to adjust to that concept emotionally. The temporary, partial amnesia that usually happens during regeneration can also enhance this. People who’ve suffered amnesia or brain damage will sometimes refer to who they were before the change as a different person. As his memories settle back into place, he feels more connected to his past.”
In addition to how regeneration affects the Doctor's state of mind, we also discussed how the Doctor's state of mind affects regeneration.
Some fans have also hypothesized that the Doctor’s final thoughts and regrets before regeneration may influence his next incarnation’s behavior. The First Doctor knew he was irascible and bad tempered, so he changed into a more jovial, outgoing person. Thus was born the Second Doctor. As Professor Langley puts it: “Each new Doctor seems to be a reaction to the last one. . . . As he’s looking back on his last life just before regeneration, thinking about how he could’ve been different, it could be like a person focusing on something just before sleep and then having that idea become an influence in their dreams.”
Distraught over actions taken by an incarnation called the War Doctor (played by John Hurt, age 73 at that time), the Doctor becomes progressively more childish and younger looking over each of his next three regenerations until, thanks to the nature of time travel, the War Doctor teams up with the Tenth and Eleventh Doctors and together these three versions of the same man right a wrong from the War Doctor's time.
Having come to terms with his own past self and having lived many more years, the Eleventh Doctor has stopped repressing memories of his time as the War Doctor. The "man who forgets" has become the man who wants to remember, stressing that he will forget none of it as he regenerates yet again in last year's Christmas special, "The Time of The Doctor." The older-looking War Doctor wonders of his younger-looking future selves, "Do you have to talk like children?" He decides it is time to grow up and apparently so does his future self when the Eleventh Doctor (played by a man who'd been 26 when he got the part) becomes the Twelfth (played now by a man of age 56). Looking back on his life, the Eleventh Doctor refers to the War Doctor as "Captain Grumpy," which may explain why his next persona appears to be poised to be the grumpiest Doctor we've seen in a long time.