Tuesday, January 5, 2016

How Much do You Know About Your Own Brain?

We tend to believe we're aware of what's happening in our own brains, and also in conscious control of our behavior.  But a growing body of neuroscience and psychology research demonstrates that most of what happens inside the brain-- including the processes that cause us to select and execute behaviors-- is beyond our conscious awareness.  This has important implications for our eating behavior, body weight, and health, as I explore in my upcoming book The Hungry Brain.

Let me give you a straightforward example that illustrates how little of our brain's activity we're aware of.  It focuses on information processing by the visual system, which is one of the best-understood systems of the brain.  I drew the basic facts of this example from a recent talk by the accomplished neuroscience researcher Marcus Raichle, who studies patterns of activity in the human brain.

Consider the retina of the eye.  It's composed of more than 100 million light-sensitive cells called photoreceptors.  These cells capture ten billion (10^10) bits of information per second from your visual surroundings.  That's a huge amount of information!  In fact, it's far too much for the brain to process effectively.

Before the information even leaves the retina, it goes through its first stage of processing and compression.  By the time the information enters the optic nerve that connects the retina to the brain, it has been compressed down to six million (6 x 10^6) bits per second-- a reduction of nearly 1,700-fold.  This is because, instead of passing along a precise copy of the visual field, the retina begins extracting salient information from it and passing that along instead.  This is similar to how image compression works on your computer (e.g., bitmap to JPEG format).

But the compression doesn't end there.  Once the information reaches the visual cortex of your brain, it's compressed down to ten thousand (10^4) bits per second.  The brain does this by further extracting meaningful information from the retinal data, translating it into increasingly abstract terms, and ignoring irrelevant information.  Now the information is starting to resemble vector graphics more than a JPEG file.  Rather than specifying the position of individual "pixels", the information denotes patterns and objects and how they're moving.

From the visual cortex, researchers estimate that less than 100 (10^2) bits per second of visual information reaches our conscious awareness.  That's only 0.000001 percent of the information your retinal photoreceptors registered, and 0.01 percent of the information that entered your brain.  This information is highly processed and filtered-- so much so, that it's predominantly conceptual at that point.  You don't see each individual hair on your friend's head and each stitch in his Christmas sweater; you just see your friend wearing a Christmas sweater with reindeer on it.  And if something irrelevant is happening behind him, you don't see it at all.  If you don't believe that, watch this video.

Since the processing power of the conscious brain is quite limited, the non-conscious brain feeds it information on a need-to-know basis.  You may not actually be consciously seeing much at all if you're listening to something intently, and you probably won't see something in your left visual field if you're paying attention to the right.  Yet, non-conscious parts of your brain are still monitoring everything outside and inside your body, looking for important signals that could be worth alerting the conscious brain.  For example, if you're trying to cross the street and something large in your peripheral vision is moving rapidly toward you, it will get your attention even if you were focusing on a billboard a moment ago.

This is consistent with the research of the Nobel Prize-winning psychologist Daniel Kahneman, who wrote the wonderful book Thinking, Fast and Slow.  Kahneman contends that the brain can be conceptually divided into two "systems".  System 1 is fast, intuitive, automatic, and non-conscious.  System 2 is slow, effortful, deliberative, and conscious.  Since system 2 is what we perceive, we think it's who we are, but in fact Kahneman believes that system 1 does most of our processing and guides most of our everyday behaviors.  System 1 is not one thing, but rather a diverse collection of ancient, non-conscious brain circuits.

The visual system example I explained above is one illustration of how neuroscience research supports Kahneman's idea.  What we perceive is only a small fraction of what's happening inside our very own brains!  That's kind of amazing, isn't it?  It's also counterintuitive, because we aren't aware of what we can't perceive, so we tend to intuitively think that our conscious brain is all that exists.

My primary interests are eating behavior and body fatness, and that's what my book is about.  As it turns out, the idea that our brains are primarily non-conscious has important implications for understanding how we eat and what we weigh.  If we're primarily conscious, rational beings, then the best way to guide our behavior in a slimming direction is to consciously regulate the number of calories entering and leaving the body.  This is typified by the "eat less, move more" approach to weight loss, which works extremely well in metabolic ward studies where behavior is externally controlled, but not so well in real life.

On the other hand, if our behavior is often guided by non-conscious processes that are more impulsive than rational, we'll need a different approach: identify the signals that influence these processes, and provide signals that align our impulses with our conscious goals of leanness and health.

While both the conscious and the non-conscious brain are important for behavior, ultimately I believe we'll get better, easier, and more sustainable outcomes by acknowledging that the non-conscious brain is often holding the reins of our behavior.


Scott Pierce said...

This might seem silly, but I've thought a lot about conscious thinking impacting epigenitics. Think of a Neanderthal being negatively impacted by louse on their hairy back, which, in turn, turns off the genes that grow such hair. Now, apply the same process to unconscious, system 1 thinking? It is an evolutionary process on steroids.

Todd Hargrove said...

Awesome post Stephan! This is a great example of something I try to get across about the processing of nociception - all of the filtering and weeding out of sensory info. And the “top down” modulation as well - if the brain decides an area is not under threat, it will cause the spinal cord to ignore nociception in the same way that the brain ignores visual information that is considered unimportant. If I knew about this cool info I would have put it in my book. :)

Thorgal Aegirsson said...

Hi Stephan,

Yes, it does make a lot of sense in retrospect. It's also applicable in other contexts.
In any case, this is where the power of meditation should become obvious. If our conscious part tends to believe that it is all there is, when in fact the unconscious part is the true rein holder (for after all, it feeds only bits to the conscious part), you understand that meditation allows one to expand awareness to processes that are most of the time happening under its radar by shutting down thought processing as much as possible. You just sit there being aware but without abstract thinking. Only then do you start to feel / become aware of underlying processes that most of the time happen unnoticed (one's breathing, heart pumping, subtle air drafts, temperature changes, etc). When one does this with increasing commitment on a daily basis, incredible things tend to happen that are too subtle to describe.

Phil Koop said...

Another of Kahneman's dichotomies is the "remembering self" versus the "experiencing self." This has a connection to reward: on New Year's day, the remembering self may regret actions taken the night before, but at the time it seemed like a good idea to the experiencing self.

When reward is coupled with discomfort, this can cut the other way. One of my wife's mottos is "the experiencing self always gets screwed." She usually says this about 120km into a 185 km bike ride.

Ben Kennedy said...

One phenomenon that I have noticed along these lines occurs when driving. Sometimes on my way home I am lost in thought over whatever the issue is of the day. Later, I realize that because I have been thinking rather intently, I have no memory whatsoever of actually driving on the streets I know I just rode on. This includes things like stopping at traffic signals and making turns. The unconscious part of my brain actually drives my car while I am completely zoned out

Ash Simmonds said...

@Todd - also:

"To test the effects of a ketone-based metabolism on pain and inflammation directly, rats were fed a control diet or ketogenic diet ad libitum for 3–4 weeks. They were then subject to hindpaw thermal nociception (burning their feet) as a pain measure.

Independent of age, maintenance on a ketogenic diet reduced the peripheral inflammatory response significantly as measured by paw swelling and plasma extravasation. The ketogenic diet also induced significant thermal hypoalgesia independent of age, shown by increased hindpaw withdrawal latency in the hotplate nociception test."

- Reduced Pain and Inflammation in Juvenile and Adult Rats Fed a Ketogenic Diet

RLL said...

There is a possible connection between this posting and your last one on back pain. Pain can exist mostly in the brain, and very much be real. I suffered increasingly severe shoulder pain, quite ignorable in the daytime and while weight lifting, but greatly interfering with sleep at nighttime. There are two meds, one an anti-depressant and the other an anticonvulsant which help many, but not all, people.

A rough analogy is that a pain message to the brain turns on a pain circuit, but the brain does not turn off that circuit when the pain stops. The meds while not actually stopping pain in the shoulder prevent the brain pain circuit from 'hyperactivity'.

Stylooke said...

Hi Stephan,

I really think this touches on some of the Buddhist goals, whereby yogis try to seek understanding of their 'subconcious' by mindfully intercepting mind states before they are even created.

fMRI studies on highly trained practitioners have indeed shown extraordinary results, (e.g. the studies on lama öser by richard davidson). Apparently he was able to nearly completely filter our the loud sound of a gunshot through sheer meditation.

Needless to say, most of us 'Westerners' (myself included) live in a mostly subconsious state whereby we are hardly mindful. Thanks for the post,
Best, Nils

Unknown said...

Largely on the same topic, I highly recommend "The Happiness Hypothesis" by psychologist Jonathan Haidt.

John said...

Its amazing that your senses can conflict and rectify in ways that defy your conscious knowledge.

Like with the McGurk Effect


You can know how it works and still your perception is influenced.

Gearóid said...

I am aware of all of this. I was a histopathologist and the best and most careful pathologist misses stuff on slides BECAUSE of the way the visual system works. Stuff is filtered out.
Nothing new for me here, Stephan!

thhq said...

@Gearoid I miss stuff on slides because I fall asleep. I believe that my body releases melatonin as soon as the lights dim, with an extra shot after the 25th slide.

I spent a career compressing data. 4000 word lab reports had to be reduced into clear 100-200 word summaries. I had to communicate as clearly and briefly as possible for my audience. They rarely asked for the full set of graphs, tables and literature references in the full report. Their time was more valuable than mine, and succinct communication was needed for them to make major decisions to move projects forward.

Journalists don't think like research scientists. When I read Gary Taubes' agonizing over how to keep Good Calories Bad Calories down to 400,000 words I don't feel any pity. He should have been working on how to reduce it to a concise 200 word abstract. This would have spared us the long trip through his cherry orchard.

When I spend my time reading 400,000 words it'll be reading Tolstoy. Though I would read GCBC if someone paid me $500. Money is rewarding.

Ellie said...

I'm so glad to see you blogging about this concept. As a holistic health coach I've been face to face with my client's subconscious eating and behaviour triggers for over 15 years. It's been so challenging to get people to change their behaviours that it has prompted me to move my practice into areas of re-wiring subconscious belief systems, even those that are wired into our primitive evolutionary psychology such as "when life is painful(or stressful), seek pleasure through food". To me the concept is blatantly obvious, but it's incredible how much convincing I have to do to show a client that they want to eat cake because their boss (or spouse, or a guy in traffic) made them FEEL something uncomfortable.