Your ability to experience a stable, coherent sense of self is truly a miracle.
Each of us experience profound changes across the course of our lifetime, growing from infants into adults, learning new things, forgetting others, forging fresh relationships and losing old ones – all interspersed with prolonged interludes of dreams and blankness each and every night.
And yet, throughout it all, we still have a sense of being the same person. Ultimately, this comes down to an ongoing construction process operating in the brain, which is probably more malleable and fragile than you might think.
Classic research in the latter half of the 20th century involved studying people who’d had the two halves of their brain severed as a radical treatment for epilepsy.
This had some bizarre consequences, including patients sometimes performing contradictory actions – such as one hand doing up buttons while the other undid them. Yet throughout, the patients retained a coherent sense of self.
They even invented reasons to explain away their bizarre behaviour – their brains were literally making up explanations on the fly to preserve the narrative of a unified self.
In healthy people, psychology studies have revealed the quirks of memory that help to reinforce this constructed sense of self.
For instance, we’re more likely to recall and rehearse memories that are consistent with how we see ourselves. Imagine you think of yourself as an introvert – it’s likely you’ll find it easier to access and describe memories from your past that support this idea of the kind of person you are.
You’re effectively editing your autobiography to fit your current self-concept.
A key region orchestrating this construction is the medial prefrontal cortex, which sits right at the front of your brain, just behind your forehead.
In studies, when researchers ask people to identify which traits best describe them, either now or in the future, it’s this part of the brain that flickers into action, far more than when making similar judgments about other people.
Our constructed sense of self also extends to the stuff we own. When people are put in a brain scanner and asked to view a series of objects, the medial prefrontal cortex tends to light up when they see their possessions. But not when they’re shown a random object that doesn’t belong to them.
This shows how quickly and flexibly our brains redraw the boundaries of self.
Memory processes are also crucial to this ongoing construction.
Damage to the hippocampus (located deep in the brain, in line with the temples) can stop people from being able to imagine themselves in the past – or in the future – revealing how dependent our sense of continuous identity is on active brain processes.
Your brain doesn’t just construct your sense of self through time, it also maintains it in space, so that you have a stable feeling of ownership of your body.
A different part of the brain, known as the temporo-parietal junction (located behind your ears), plays an important role in this aspect of your identity.
In a study from 2005, when researchers electrically stimulated this brain region during brain surgery, it triggered an out-of-body experience in the patients. They felt as if they were floating outside of themselves.
In short, our sense of a stable self usually feels utterly convincing, yet it can be fractured by brain damage and clever neurological experiments.
Taken together, the evidence suggests your sense of me-ness is a construction, one that your brain works tirelessly to maintain.
This article is an answer to the question (asked by Frank Ross, Southampton) 'How does my brain create my sense of self?'
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