Why The Neuroscience of Identity is Bound to Time and Memory
When you look up at a star in the night sky, you do not see the star directly, but the light that the star is emitting. Even the closest stars are several light years away, meaning that it takes literal years for the light to reach our eye. What you see is what the star looked like years, and sometimes decades, ago.
To stargaze is to stare directly into the past.
This may sound like astronomy trivia, but down on Earth, this is how we perceive everything that catches our senses, albiet on a less extreme timescale. We're always perceiving the past. What we experience as the "now" transpired about half a second before - roughly the time it takes for our brains to process and interpret the sensory input we're taking.
In this way, our very sense of "now" is not really "now" at all. The present moment, as we feel it, is what the world was like a second or so prior. Our brains are always playing catch up.
Our feeling of "now" is a construction of the brain. We know this because the brain processes sensory input at slightly different rates. Vision, for example, is processed a fraction quicker than sound. And yet, we don't feel as if the world we see is moving faster than what we hear - everything feels coherent and simultaneous. And we have the brain's subtle, unconscious processing to thank for it.
But what happens when these processes are disrupted? We very easily take for granted that the world as we perceive it is happening now and that everything we take in from it - the sights, sounds, smells, are happening simultaneously. It's the foundational thread that connects us to reality. So what happens when this unwinds?
We see that time perception isn't an isolated mental ability. The neuroscience of time isn't as simple as having an "internal clock" as we sometimes declare in everyday conversation. Instead, the feeling of time exists within a tangled story of perception, memory, and, ultimately, our sense of identity.
How The Neuroscience of Time Perception Unwinds
Consider how we process simple visual information across time and place. We accept as a given that time flows forward in a smooth, and consistent manner. Provided the thing we're watching isn't moving at an extreme speed, we can track its movement with little effort. Watching a runner jog by from your office window, their movement appears fluid and continuous. Time moves steadily. But what if it suddenly didn't?
Following a stroke that damaged regions of his visual cortex and right parietal lobe, a 58-year-old Japanese man began to experience time very differently. Instead of seeing fluid motion, he started seeing the world in static snapshots every few seconds. The visual world became a series of discontinuous freeze frames. For example, when he tried to pour tea into a cup, it appeared frozen.
He experienced a rare condition called Akinetopsia, in which one loses the ability to process fluid motion. It was as if he witnessed the world flash underneath a strobe light. The jogger outside your office window would appear frozen in place for several seconds, and then suddenly jump several yards ahead.
This lack of fluidity was specific to vision. Everything else moved in the same fluid speed. As a result, it became challenging to follow conversations with people face to face. Sound played at regular speed, while vision lagged behind in second-long intervals.
The continuity and coherence of momentary experience, which we all naturally assume as a metaphysical truth, has been undone.
How The Brain Connects Memory and Time
The case of Akinetopsia illustrates how our sense of "now" - a fragile construction held in place by the brain, can be disentangled into its constituent sensory parts. Time still marches forward, but not all at once. It turns out that the inverse is also true: a "now," in all of its coherence and immediacy, can be all there is.
Consider the case of Clive Wearing, who experienced exactly this; a life frozen in now. Or more accurately, a life comprised of brief, distinct, and truly unconnected "nows."
Clive suffered from severe Amnesia, which resulted from an infection in his medial temporal lobe - a region crucial for memory. Amnesia has two forms: Retrograde Amnesia is difficulty remembering anything from the past, while anterograde Amnesia is difficulty forming new memories. A mild version of either has devastating, life-changing effects. Clive had severe cases of both.
His infection began in 1985, when Clive was 47, and wiped out nearly all of his existing memories. And from the start of the brain injury, he couldn't remember anything new. Each person he met, no matter how many encounters he had with them before, felt to him like the first time.
In fact, the people he met felt like the first people he had ever seen. As he describes in a 2005 documentary, describing his condition:
"You're the first human beings I've seen, the three of you. Two men and one lady. The first ... people I've seen since I've been ill. No difference between day and night. No thoughts at all. No dreams. Day and night, the same – blank."
Clive's entire experience - the sense of where he is, what he's doing, and even, who he is, exists in distinct, 30-second bursts. As his wife, Deborah, describes,
"It was as if every waking moment was the first waking moment. Clive was under the constant impression that he had just emerged from unconsciousness because he had no evidence in his own mind of ever being awake before. . . . "I haven't heard anything, seen anything, touched anything, smelled anything,"
A life wholly contained in the "now."
What Clive Rearing Teaches Us About Time Perception and Identity
As psychologist Marc Whittman describes, the duration of felt experience is about 2.5 seconds. That's the essential bandwidth we take in the world, what William James coined as "the specious present."
By this measurement, Clive had a few precious intervals of felt experience before starting from scratch. His diaries, which his wife published, make for disturbing reading. They are a series of increasingly intense proclamations of "finally" awakening, with each crossed out and replaced by another just a brief time later:
8:31am Now I am really, completely awake
9:06am Now I am perfectly, overwhelmingly awake
9:34am Now I am superlatively, actually awake
Clive's memory effectively "resets" every 30 seconds. And in a sense, it's not only Clive's memory but his entire identity and self-hood. Imagine blinking your eyes, and when your eyelids part, your entire memory is gone. You have no idea where you are, how you got there, and what you were doing a moment earlier. It's disorienting to imagine. And this is Clive's life, in perpetuity.
Clive's experience underscores the crucial importance of memory to our sense of being a self. It's a strange thought. We wake up each morning as a slightly different person, and yet, we feel as though we're an enduring entity moving through time. What's the glue that holds us together? It's our memory.
As we've seen with dissociative fugue, disturbances to memory can blur our sense of identity. Why are we if not for our unique connection to our unique past? As neuroscientist and memory expert James McGaugh states, "Memory is the most important mental ability. Without memory, there would be no human being."
In a very real sense, memory - in its ability to tether us to time, is our self.
Final Thoughts on The Neuroscience of Identity
Time feels like a truism, a property etched into the very fabric of reality. But as we've seen, our perception of time is a band of threads woven together by the brain. Our connection to it is much more fragile than we realize. When these threads become undone - as in the case of damage to the brain, we're thrown into a netherworld where our very identity and sense of self ceases to exist.
Touchingly, Clive retains memory for two things: music, and his loving wife, Deborah. It's no accident that these are the two islands that remain. Neuroscience research finds that musical memory and memory of deeply emotional experiences - such as love, are distributed far and wide in the brain. In many cases of neurological damage, as with Clive, they remain when everything else is lost.
His sense of being a continuous self, so far as it exists, does so amidst these two elements. As Deborah described to the late neurologist Oliver Sachs, who worked closely with Clive for many years, "Clive's at-homeness in music and in his love for me is where he transcends amnesia and finds continuum."
In her memoir about her husband, Forever Today, Deborah describes how Clive often feels an immense, incalculable distance between their meetings. In one instance, after being gone only 15 minutes, she found a message from him: "Please come and see me, darling—it's been ages since I've seen you. Please fly here at the speed of light."
It's perhaps no accident he used that specific turn of phrase. For Clive, the distance must have felt like lightyears.
Photo by Stephan Valentin via UnSplash
About the author
Matt Johnson, PhD is a researcher, writer, and consumer neuroscientist focusing on the application of psychology to branding. He is the author of the best-selling consumer psychology book Blindsight, and Branding That Means Business (Economist Books, Fall 2022). Contact Matt for speaking engagements, opportunities to collaborate, or just to say hello
References for The Neuroscience of Time, Memory Psychology and The Perception of Self
Bourne, C, (2006) A Future for Presentism, Oxford: Clarendon Press.
James, W, (1890), The Principles of Psychology, New York: Henry Holt.
Myers, G, (1971), ‘James on Time Perception’, Philosophy of Science, 38: 353–60
Sacks, O. (2007), The Abyss, The New Yorker
Wittmann, M. (2018). Altered states of consciousness: Experiences out of time and self. MIT Press.
