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Dopamine - incredibly critical and yet critically misunderstood

Popular culture is full of references to dopamine:

"Dopamine is about reward! When I eat chocolate, I enjoy it. The brain produces dopamine when we enjoy it, which tells us to do it more often." 

 

Almost everyone perpetuates this understanding of dopamine = reward
 

But this is inaccurate. Dopamine is about reward, but it is much more, and has unique caveats. 

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Photo credit: The AwkwardYeti

Level 1 - At the most basic level, dopamine is related to reward

At a basic level of understanding, dopamine does trigger upon receiving a reward. But the definition of "reward" is far broader than what is commonly associated. Let's go through some examples:
 

  • Let's say you really like chocolate cake. Naturally, upon consumption, dopamine is released, making you feel good.  
    (this is however not the full story. What happens if we "silence" the part of the brain that produces dopamine, the ventral tegmental, to prevent it from activating? Stay tuned, we will explore this in level 3)

  • Basic needs like food and sex cause a dopamine release in every species ever investigated. However, more complex species can trigger the pleasure felt with dopamine release through thought rather than actual experience

    • humans trigger dopamine release simply thinking about sex (this has all sorts of interesting implications on the difference between our perception and the actual reality)​

  • What happens when there are 2 different rewards? The one that brings more pleasure triggers more dopamine. In this uncomfortably interesting and somewhat hilarious experiment, thirsty male rhesus monkeys were given a choice between their favourite drink - cherry juice - or to look at computer images of the backsides of female monkeys. Thirst be damned because all the monkeys chose to look at the pictures. Monkeys would also choose to look at pictures of the faces of high-status "celebrity monkeys", but would have to be bribed with more cherry juice to even look at the faces of low-status" monkeys.  
     

  • The definition of "reward' can be most varied. Let's say some folks are given a record of someone who is very popular, wealthy, attractive, and has great academic accomplishments. For those who reported envy, the regions of the brain involved in pain perception light up - in other words, people literally feel pain from envy. Now let's say this hypothetical person receives good fortune, e.g. he/she wins a major award. What happens? Even more pain activation. But what happens if the person experiences misfortune - say he fumbles and screws up on a very big project? Well, dopamine is triggered. Our dopaminergic system activates in response to schadenfreude, where we feel glad to see someone fall from grace. 
     

  • It can go further. Take the trust game that we covered in another chapterIn a 2 player game, a player can receive:

    • a moderate reward by cooperating with the other player; or

    • a larger reward by cheating the other player's trust.

  • Both options lead to an increase in dopamine, but there is a larger increase in dopamine in cooperation, even though the monetary reward is smaller

    • Additionally, we also learn that people are motivated to seek revenge. Punishing the cheating player causes a very large spike in dopamine. ​
       

Dopamine is regulated by habituation, expectations, and relativity. The excellent study by Cambridge's Wolfram Schultz allows us to understand this better:

  • A monkey is kept in a room with a brain scanner on. There is a lever in the room. 

  • If a light comes on, and the monkey presses the lever 10 times, the monkey is rewarded with raisins.

  • What if the reward is unexpectedly higher or comes earlier than normal? The dopamine level surges, more dopamine is produced; more pleasure.

  • Conversely, what if the reward is unexpectedly lower or comes later than normal? The dopamine level becomes a fraction of the original that is produced - less pleasure. 

  • Finally, what if the same reward is given time and time again, over a very long period of time? The dopamine produced will decline over time - your brain gets habituated to the reward, it's no longer as pleasurable. 
     

So dopamine follows the law of diminishing returnsIf you have already eaten a kilogram of chocolate and you're full to the point of passing out, being presented with the most decadent and delicious looking chocolate bar barely triggers dopamine. But if you've been on a diet even a picture of the chocolate bar causes your dopamine to go through the roof. 
 

Additionally, dopamine is produced not from absolute values, but triggers relative to expectations: Person A and Person B perform the same task to the same standards. Person A is used to receiving $10, but is now rewarded with a $12 payment. Person B is used to receiving $100, but now is paid $96. Even though B, in absolute terms, receives 8x what A received, A feels more pleasure. 
 

The relative nature of dopamine secretion extends even to punishments. Say you sit in a chair where you periodically receive either a moderate or a heavy shock. Over time, your brain starts emitting dopamine when you receive the moderate shock, it is a "reward" in the sense that it is less punishment relative to the heavy shock, even though you are literally in pain.
 

And it is important that the system works this way. Because there so many rewards in this world, your brain needs to differentiate between the levels of pleasure. Winning the lottery must feel more pleasurable than picking up $1 off the streets. Scoring a date with the girl of your dreams must feel more valuable than getting an extra serving of chicken for lunch. But after scoring a date with the same girl 50,000 times, it still feels good, just less good (unless you change something about the date).
 

The relativism and habitation of our dopamine system become more prominent in the modern world:

  • In the past, reward was uncertain, limited and difficult to come by. ​Today, reward is at our fingertips - ordering food from many different sources, watching movies on Netflix, listening to music, buying almost anything from anywhere in the world. 

  • Because rewards are so easily accessible, and because of habituation, small rewards that used to mean something to us no longer do. For example, we no longer appreciate the hard work it takes to produce the food we consume. We are less likely to stop and appreciate the beauty of flora and fauna by the street because we've seen even prettier sights on our travels. 

  • In a world where everything comes so much faster and better than in the past, our ancestors might have thought our current generation must be very happy living in paradise.

  • But due to habituation and relativism, this is not the case. Even as the things we get to buy become better and better, we ironically find satisfaction harder to come by. We constantly want things even faster and even better. This could be one contributory factor as to why the joy of material possessions declines over time; there is always something newer and better that we want to get. Rampant consumerism is here to stay. That is, unless we tie some meaning to what we own, or when we actively recognise that this impulse to keep buying comes just from the habituation of dopamine in our brains, and we can always make a different choice. 

Ok, so that's the straightforward part. Now let's move on to the more interesting bits.​

Level 2 - the anticipation

So that's settled than isn't it? Dopamine = pleasure, even if the meaning of pleasure could be quite varied.

Not even close. Take gambling for example. Most gamblers end up losing. Hence there is no rewards/pleasure. In fact most of the time, their reward is negative. Yet they continue to be excited about gambling. What about folks who are on Tinder, swiping profile after profile? Does it require a match for them to find pleasure? Or is the swiping itself pleasurable?

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We turn back to our trustworthy if long-suffering lab monkeys. What if instead of measuring the dopamine release after a reward is given, we measure the release of dopamine before?

  • Back to our experiment: monkeys (wearing a brain scanner) are placed in a room with a lever

  • when a light comes on, and the monkey pushes the lever, the monkey gets a reward.

  • As the right of the graph above shows, after the monkey gets a reward, there is an increase in dopamine, as we'd expect.

  • But look at the left of the graph. What happens to dopamine release before the monkey even gets the reward? Once the signal comes on, before the monkey even pushes the lever, there is a humongous surge of dopamine. The monkey feel pleasure before the reward!

  • And here we notice the key finding that helps us understand the 2nd level of how dopamine works: the pleasure doesn't need to come when the reward comes; pleasure can come in anticipation of the reward. The pleasure from anticipation can be far greater than the pleasure of the actual reward


Have you ever had an urgent craving for a particular food?
You went in search of it. 

You know the exact place to get a very good version of what you want.
And you eat it. Now think back on your experience.
At which point did you feel the most intense emotions?
Sure, it was pleasurable eating the food.
But can you remember the excitement and anticipation?
How good you felt before you ate anything,

but know you will get to eat it soon?

The actual eating almost becomes an afterthought. Just like the lab monkey, we get more pleasure in anticipation of a reward than the reward itself. Or in the vernacular of my younger nephew: This picture is going to get a ton of likes on Instagram! (instead of this picture has gotten a ton of likes)

Further research by Huda Akil of the University of Michigan provides an even more nuanced understanding of anticipatory dopamine.

  • Let's say the monkeys are in the same experiment as above.

  • The only difference is that: the left side of the room is where the light comes on and where the lever is. The right side of the room is where the reward is dispensed.

  • Amazingly, the monkeys prefer to hang out on the left side of the room. While the right side is where they get the reward, the left side is where they get the signal in anticipation of the reward.

 

This also explains why people who have kicked a habit suddenly feel an intense urge to indulge again. When a former alcoholic walks past his favourite alcohol store on his favourite street where he spent many happy hours drinking, his dopaminergic system triggers in anticipation of the pleasure that had been so familiar to him. 

This is why slot machines are so addictive. Because they are designed to represent a "near-miss" each time it's played - the player feels like he was so close to getting the reward. His/her anticipation goes up. 

Or that people feel really good on Fridays even though they have to work, anticipating the coming of the weekend. Yet they feel terrible on Sunday even though there is no work, anticipating the coming of the workweek.

It is why all social media apps have a "feed" or "homepage" element designed in exactly the way it is, where you can keep scrolling down to find something interesting. That scrolling motion is the anticipation
(which also explains why social media apps can get away with more and more advertising - because people are still compelled to keep scrolling in anticipation of the reward). 

It's what makes many sports exciting. Think about what most sports are like - baseball, basketball, soccer -  most of the time, there are more misses than hits. But because the players are not far off in their misses, we're excited by the anticipation that they hit it (soon). 

That it is the anticipation of pleasure and not pleasure itself that makes us feel good is an incredibly critical point which we will come back too later.

 

There is one final and important point to add to this section:

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The story so far is that a light comes on, the monkey pushes a lever, and there is a reward. What if the reward is uncertain? What if the reward only comes 50% of the time? Well, something quite remarkable.

  • Look at the graph above. 

  • In the passage of time between signal and work, and after the reward is given, the results are similar.

  • But look at the passage of time between work and reward: 

    • When the reward comes 100% of the time - there is no further dopamine released.

    • But when the reward comes 50% of the time - there is a humongous surge in dopamine!

    • What if we adjusted so the reward comes 25% of the time or 75% of the time? 75% is a higher likelihood than 25% or 50% of getting a reward, so is there more dopamine?

    • The answer is no. The surge in anticipatory dopamine between work and reward peaks at 50%, when the uncertainty is highest


Consider the example of social media posts. 
Are people more excited when they have just posted,

and are waiting for responses (which are somewhat uncertain?)

Or are they more excited when they actually get a reaction?

Additionally, if someone likes your post all the time, 

are you still excited about the "like"? 
What if this person suddenly doesn't "like" the post?

We return to the case raised at the start of this section: why do gamblers go back gambling again and again even though they often don't get rewarded? Well, the secret to this is that Las Vegas and other casinos perfectly understand the workings of our dopaminergic systems. Games are designed where gamblers constantly experience near-misses:

  • The slot machines where 2 out of 3 columns tend to be alike.

  • Roulette where red and black is just 1 slot apart.

  • Blackjack where 1 card makes the difference.
     

Gamblers always have an elevated sense of "if only" and "so nearly". Add this on to the free-flow of alcohol, the lack of time cues, the excitement of other gamblers, and the dopamine levels constantly surge, making gamblers want to go one more time, one more time, one more time, because the next time is going to be the winning try. And this action compelled by dopamine release nicely segues into our next section. 

Level 3 - the pursuit

In the last section, we explored how casinos trigger anticipatory dopamine so that gamblers continue gambling. Or that when people post on social media, they have the same surge in anticipatory dopamine as they wait for responses and likes. 

This is an absolutely crucial point. Dopamine isn't simply about feeling good. Dopamine isn't just about pleasure and reward.

Dopamine binds work that is needed to the reward we want to obtain.
It creates motivation that fuels goal-directed behaviour. 

Dopamine represents the joy of pursuing a reward that is not certain,

but which we know we have a good chance of attaining

We examine the monkey and the lever one final time:

  • if dopamine is inhibited (we can do so by silencing the relevant brain regions with a magnetic brain scan) after the light comes on, the monkey doesn't press the lever even though it will get a reward. This brings us back to the chocolate cake example at the very start of level 1 - it's not so much so that you don't enjoy the cake anymore if no dopamine is produced, it is that you won't even go and eat it in the first place. 

  • Conversely, if there is no light, but we electrically stimulate the ventral tegmental which then releases dopamine - the monkey presses the lever even though the familiar cue is absent. Dopamine drives action.

This understanding of how dopamine works, in turn, informs how habits are formed. In life, there are cues (like the light turning on) which signals that if we put in some work (pressing the lever), we will get a reward. Our dopamine spikes once we see the cue, making us excited about the anticipated reward, and compelling us to take action.

We could just be winding down about to go to sleep. And then you watch a video of someone eating. That is the cue. Suddenly, dopamine spikes, and you want to eat too. Your brain starts trying to convince you, find something to eat, it's not too late. Get something delivered. And if enough dopamine is produced, we succumb and we make the trip to the refrigerator, to the nearby Macdonalds, or to our favourite food delivery app. 

Habits are a big part of our lives. Find out more about habits here

Dopamine, other parts of the brain, and reward

Here's a question to consider. If dopamine is about the pursuit of a reward, what if there is an immediate reward and a longer-term reward? Which then do you pick to pursue? Or everyone's favourite example: should I cuddle up in bed to watch Netflix which is immediately enjoyable, or do I go to the gym and workout, where after some time, I might get a lot of praises about my improved physique?

In general, shorter rewards will often be more attractive to us. This is a biological reality - because our brains will not keep producing dopamine perpetually to fuel our pursuit of the longer-term reward, especially when there is an immediate alternative.
 

We call this temporal discounting - the value of something in the future is discounted because we have to wait for it.
 

There is an additional consideration of which part of the brain dopamine activates more:

  • When there is a greater projection of dopamine on our limbic system (our emotional system), we tend to pursue more immediate rewards.

  • Conversely, when there is greater activation of our pre-frontal cortex, we tend towards gratification postponement, we are willing to wait for the reward that takes longer.

This becomes easier with some examples:

  • brain scans show that people who are impatient have, as you would expect, steeper temporal discounting curves. Every additional time period causes the value of the reward to fall more than proportionately. 

  • folks who suffer from abnormalities in dopamine profile, for example, those with attention-deficit/hyperactivity disorder (ADHD), again have very steep temporal discounting curves. The immediate pursuit of the reward carries a lot more value. 

  • When we take alcohol, our pre-frontal cortex becomes more inhibited, and we become more impulsive. Our temporal discounting curve shifts - where longer-term rewards, for example building a relationship with someone, become less attractive, while shorter-term rewards, for example, sexual intercourse, becomes more attractive than if you were sober.

  • You might also have heard of the marshmallow test - a seemingly classic test of delayed gratification: put a kid in a room with one marshmallow, and tell the kid that if he can wait 15 minutes without eating the first marshmallow he will get a second marshmallow.
    Here, we see how past experiences shape our temporal discounting. Kids coming from richer backgrounds and a higher social standing are more able to hold out for a second marshmallow - because they were used to promises being kept, and probably had an experience of successfully waiting for a bigger reward. In contrast, kids who came from lower-income backgrounds found it much harder, because past experience tells them that they can't trust that a second marshmallow is really going to come. Read more about this here

But there are also instances where humans are able to delay gratification for an unbelievable amount of time, what no other animal is capable of doing: 

  • Some of us are able to go on a diet for months so that we can look good in the dress at prom or in the bathing suit in summer.

  • Some actors are able to starve themselves to look more convincing in a movie role.

  • Many of us are willing to dedicate 20 years of our lives studying, so we can get into a good university, to get a good degree (all of which might not mean anything to us), just to enable to us to get a better paying job with more money (and perhaps a better quality nursing home when we are old) 

Amazingly, we are sometimes able to delay gratification past our deaths:

  • soldiers commit their lives for their countries, for a greater chance to win the war

  • we make financial sacrifices so that we can leave something to our children

  • we make sacrifices of convenience and comfort so that we can lead this planet less damaged for future generations

  • And we can adhere to some religious practices for our shot at paradise. (at a firm atheist, my dopaminergic system cannot resist pointing out that it's unlikely there is a god, despite knowing it will have no effect on religious readers)

There are several important takeaways from this:

 

1. If we are able to find a very strong reason to do something, the reward this promises is large enough to withstand temporal discounting. Even if we don't live to see this reward in our lifetime, we get enough anticipatory dopamine to keep us on course. Or, as Viktor Frankl puts it: 
 

“Those who have a 'why' to live, can bear with almost any 'how"

2. Milestones are incredibly useful for large tasks. From ultra-distance runners to novel-writers to struggling entrepreneurs, folks that have a very large and major goal tend to find more success if they can break this goal down into smaller parts - just run for another 20 steps, just finish another 2 pages, just try to finish this next task. Finishing the smaller goal provides us with a dopamine boost, which provides intrinsic motivation that you are making progress in your pursuit of the final goal. In contrast, if we left large goals as they are without breaking them down into smaller sub-goals - we find it difficult to register the progress we are making. We might lose our intrinsic motivation because the goal seems far less achievable
 

Dopamine is a lot more complicated than what popular cultures depict it to be. But like everything else on this site, an accurate understanding of how our brain helps us to devise strategies that actually work to improve our lives. 

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