How we change what others think, feel, believe and do

The Brain's Urge System

Explanations > How the Brain Works > The Urge System

Six steps to heaven | When the system goes astray | So what?

At a fundamental level, the brain has a simple carrot-and-stick biochemical system of forcing us into action, as illustrated below (you can click on the diagram to see explanations of each part, or just follow the text below).

Six steps to heaven

1. Stimulus

The stimulus to the brain starts with a physical condition such as low blood sugar. It can also come from a visual signal from something desirable or undesirable, or even pure thought. In each case, the stimulus is a trigger for a sequence of internal events which will result in external action. 

2. Urge

The thalamus in the limbic system ('leopard brain') converts the physical need into an urge within the cortex. It is, in effect, saying 'Hey, do something! You have an unfulfilled need!' Cognitively-driven urges have a similar effect, where internal imaginings trigger an urge response.

Urges are, quite literally, urgent. They have priority and force other matters aside. They are frequently felt as a kind of 'emptiness', typically felt physically as a gnawing feeling in the abdomen.

For example the low blood-sugar gets translated in hunger. The lack of human company, especially close companionship, is a more instinctively driven situation that provides urge. Note how both give you a feeling of emptiness.

3. Desire

The cortex then translates this urge into a targeted desire for something specific, which gives us a conscious motivation towards a particular goal. The underlying urge becomes wants and needs. Wants and needs have to struggle against one another in a priority list for action now or later or not at all. The strength of the urge is thus important, with strong urges leading to needs that jump the queue, demanding immediate action.

For example the felt urge of hunger is translated into a desire for food, whilst the  urge for human company becomes a desire for company. This can be a desperate desire, as the starving person thinks of nothing but food and the love-struck individual cannot get the object of their desires out of their mind.

4. Action

Eventually the urge-desire reaches its goal and the person takes physical steps  to satisfy the internal nagging that has prodded them into action.

The action may be small or it may take significant time and effort. It may also be undesirable in some way, such as when a person on a diet does not really want to eat. This only goes to show the power of this internal motivation system to force us into even uncomfortable action.

5. Evidence

To complete the loop, the brain now needs proof that the action has been completed before it proceeds with its reward. It is not enough to remove the stimulus, for example intravenous feeding or going to a crowded place does not make you feel good.

The evidence has to come in a particular place. It is specific actions which are rewarded. Going to a restaurant is not good enough. Looking at food is not good enough. Putting it in your mouth is in the right direction. You can almost hear the brain shouting 'go on, go on'. But it is the swallowing where you feel good.

6. Reward

When the limbic system detects that we are satisfying the urge, like any motivation system it must reward to encourage continuance of the desirable behavior.

The brain rewards us in two stages. The first stage is to tell us that we are doing the right thing and to encourage us to keep doing it. Thus we get to feel satisfaction for each mouthful of food. It's as if the brain is saying ‘That’s right! Keep doing that!’

However, we can't keep eating forever and there is a point at which our bodies have sufficient input to sustain them for a while. The job of the brain is now to stop us eating. It does this by making us feel fulfilled, often by a literal feeling of being 'full'. It is as if the brain says ‘Well done! That’s enough for now.’

The gnawing emptiness is now replaced by a replete sense of completion and satisfaction as we sit back and relax in an after dinner snooze.

When the system goes astray

This system does not always work to our advantage. If it breaks in some way, then we can either find ourselves stranded and unmotivated or stuck in a cycle of repetition. 

Can't start

What if the cycle does not complete? The stimulation may be there, but somehow the chain of urge-desire-action has been broken.

One way we are unable to start doing something we should is where urges clash, and one overcomes the other. In Anorexia Nervosa, the urge to be socially accepted and the consequent desire to be fashionably thin overrides the urge to eat. Cleverly, the part of the mind that wants to be thin compensates for the painfully thin reflection by hallucinating it into a fat and undesirable person.

We can also break cycles merely by interruption. People who fast for political or religious reasons will tell you that once you have got past the day or so, it becomes increasingly easy to not eat, to the point where they have to force themselves to eat for some while before it becomes pleasurable again.

Can't stop

As well as not being able start, we can also fall into a state where we cannot stop. The 'fulfillment' signal is either broken or is overridden by a stronger urge-desire signal.

The reverse of Anorexia is over-eating. In this case, it is the system which tells us to stop which is broken. This may happen where the urge for comfort and to feel good drives us to do those things which have made us feel good in the past. Eating is thus driven less by the body's need for food as the brain's need for comfort.

Obsessive-Compulsive Disorder (OCD) is a classic syndrome where non-helpful urges fall into a can't stop cycle. These can include peculiar 'can't stop' activities, from counting and repetitive movements to collecting and other actions that others find annoying or trivial.

So what?

So this is the inner secret of how the brain prods us into action. You can use this system to change behaviors.

Breaking the cycle

To stop someone over-eating, you could provide something more desirable. When they reach for the food, show them a picture of a healthy person. You can also do the reverse, showing them a picture of a fat person. You could put a mirror on the refrigerator.

You can also break cycles by removing stimuli. So take away the food. Or replace it with fruit and vegetables. Make mealtimes short. Fix the times when you eat.

Introducing other urges

You can also overpower them with other urges that blot out and distract from the urge you want to extinguish.

Get them interested in sport and being healthy. Take them out to dinner and let them pay. Go to expensive restaurants. Put something that smells nasty in the refrigerator. 

Changing the rewards

Finally, you can attack the end-point, the rewards they receive for both acting and completing the action.

Make the food bland so it doesn't taste so good. Change the texture or appearance. Watch a horror movie or listen to disliked music during the meal. 

Give completion awards earlier and make them significant. So eat before going to the theater, but go late so you've only a short period before the play. Have a small first course followed quickly by a very tasty second course.

See also

Willpower

Carter, Rita (2000), Mapping the Mind, University of California Press