Humans

7. Feedback in Humans

We have already looked at various biochemical mechanisms in humans, as well as in other organisms. This chapter looks more generally at how feedback mechanisms are involved in various aspects of human behaviour.

Human Motor control

It is one of the frustrating things about trying to make robots that tasks which appear very simple to us, like drinking a glass of water, brushing our teeth or tying shoelaces are actually incredibly difficult to automate. The movements involve a lot of ‘degrees of freedom’ – basically movements that are independent of each other. They also need precise control in holding and releasing objects, and an overall understanding of the task, and a lot more smarts such as object recognition.

Something as ‘simple’ as eating - chewing and swallowing, is in fact fiendishly complicated. Large numbers of muscles and sensors are in play to taste, filter, manipulate, crush and masticate a mouthful. No one (as far as I know) has even tried to automate this process accurately.

Understanding exactly what goes on when we do these simple things is still a work in progress, as is trying to get robots to do them, although good progress is being made with the large amounts of processing power now available.

But fundamentally, any motor control (such as picking up an object) has to involve negative feedback. Without any, we would be back to the ‘blind driving’ problem. Try picking up something with your eyes closed and wearing thick gloves. When we reach for an object, we are getting feedback from a variety of means. Firstly we can see our hand and arm in relation to the object. We are getting a continuous message from or brain as to how far a way we are, and what direction we are moving in. If we overshoot (as babies do when learning) we can see that too, and make necessary corrections. Then we have proprioceptors in our muscles to tell us where they are, even if our eyes are closed. Finally we have touch as we close in on the object (and maybe smell and sound can help us sometimes).

So everything we do, from getting out of bed, walking, eating, drinking, driving, fighting (well, some people do), all involve feedback. We simply could not exist without it.

And if all of us use feedback, some of us use more than others. Sports involve this kind of feedback all the time. Recent research has shown that talented sports people have built in ‘maps’ that tell them where they are in relation to, say, a football. We all have them to some extent, but gifted sports people have better maps of the kind that, well, make them good at ball games. Of course, we have always known that something like this must be going on – we call it ‘ball sense’.

Biofeedback

This is a technique that can be learnt to control body functions which are normally considered to be under involuntary control. The most common example is blood pressure, along with the closely connect pulse rate.

The feedback is provided by some monitoring equipment, such as a screen display of blood pressure. The feedback can then be seen and used by the patient to try and lower the pressure displayed. Any action he takes which reduces it can be reinforced, and those that increase it can be avoided.

Although the degree of control that can be acquired is limited, it can be used to treat several problems such as tension and migraine headaches, tics, and muscle tension. It has even shown promise in helping patients to recover the use of paralysed limbs.

Human behaviour

Epidemics

When someone gets an infectious disease, he can pass it on to someone else (obviously). That person can pass it to another, and so on. If the rate at which this passing on is fast enough, it leads to an epidemic. Epidemiology is (as usual) pretty complicated, but the basic process is fairly simple.

This is another example of the ‘avalanche’ effect. Each passing of the infection is not an example of feedback, but the way in which the epidemic as a whole grows is a kind of positive feedback. The more people that get infected, then the more possibilities there are of further infections. This is similar to the kind of thing in ‘explosions’, which is whey we sometimes use that term to describe a very rapid epidemic.

Social Networks

There has been a lot of interest in social networks recently. A lot of it has centred around the ‘six steps to anyone’ idea – the discovery that you can reach almost anyone in the world through a chain of six contacts who know each other. There is also the ‘Kevin Bacon’ index – a measure of how busy an actor has been by measuring how many contacts with other actors is need to reach a film in which Kevin Bacon appears. These ideas are covered in detail in such books as Malcolm Gladwell’s The Tipping Point, and Philip Ball’s Critical Mass.

And now we have web based social networks such as Myspace, Facebook and Twitter, though other web based groups have been around since the early days of Compuserve, Aol, the Well and others. In some ways social networks can behave like crowds, which in a sense they are – only distributed over a wide area. And of course, they are more diffuse in both time and space, so do not tend to exhibit behaviour quite like hysteria.

Recent research however has shown that they can produce surprising results. Behaviour patterns such as happiness, depression and even obesity, can be spread through social networks like Facebook. Studies have shown that there is a greater correlation in these behaviours between people who are closely linked on Facebook than those who are not. The linkage acts up to three degrees of separation, so person A who is a ‘friend’ of person B who is a friend of C who is a friend of D shows some correlation between himself and D. Though naturally the correlation is stronger between immediate contacts. And, as in all social contacts, there is always some feedback going on.

Crowds and social networks are both similar to swarms that I discussed in the section on Biology. Behaviour is adapted according to the observed behaviour of close neighbours. Because humans have complex minds, and complex technology, the observation and adaptation in these networks can be more complex than in swarms, and closeness does not have to imply physical closeness, but close connectivity.

The Wisdom of Crowds

There has also been a lot of interest in ‘the wisdom of crowds’ in the light of social networks and other internet connectivity. The point is that, especially these days, no one person can possess more than a minute fraction of all the knowledge in the world. But if you can access in an integrated fashion the knowledge, talent, experience and wisdom of a large group of people, then you could have something potentially more powerful and wise than any one person. You have, in fact, some kind of composite mind.

The wisdom of crowds has been with us for a long time, since Adam Smith and his ‘invisible hand’ of market forces, as I shall discuss in Economics. And ever since democracy was invented, there has been some kind of trust in the wisdom shown by a widely based franchise.

But the internet has increased the number of ways in which this effect can be observed. Public opinion can be tested more or less immediately, and perhaps more reliably than by asking people questions. Opinion polls are always subject to the problem that people may give answers that they think that they should give, rather than that which they actually hold. Recent use of Google’s search data has shown that you can observe changes in the public’s economic activity more accurately than by any other means, and can be used to modify economic models. It shows what people are actually thinking by the questions they ask, including how they are thinking of spending their money. The net can also be used to quickly hold tests of public opinion, and to form pressure groups and create petitions. These can now be global in scope, and can form powerful lobbies which are capable of causing change to take place. Look at Avaaz for example.

There are also an increasing number of efforts to form internet groups that can combine together to do useful work. Some such efforts have been going on for a while, such as the search for extra terrestrial life (SETI), and simulating protein molecule folding. These have centred around the ability to link large numbers of PCs around the world to perform very heavy duty processing. I am rather fond of this trend because I wrote an essay some years back called ‘The Global Computer’ which discussed the general idea (and it is still on my web site atiyah.plus.com).

These efforts involved little input from the network group other than providing computer power. More recently there has been an increased emphasis on actually getting the group to contribute their personal skills and effort. For example, there is a Facebook ‘crowd source’ of 56,000 people in 101 countries working on an animation film by both producing short animation clips and voting on them to see which the crowd thinks best (see www.massanimation.com).

Hysteria and the Media

Mass hysteria and crowd behaviour spreads something like an epidemic. The more people who behave hysterically, or in some extreme way, the more likely that others will follow them. Mob violence can spread like a fire.

The media plays a part in this kind of spreading. A classic example was the death of Princess Diana. A natural expression of sympathy was magnified into an astonishing outburst of public mourning, and was hugely magnified by continuous coverage by the media. After a point, the media was no longer covering the original event, but the reaction to it, and other media coverage. In other words, the media was covering the media, which is a classic example of a feedback loop.

In fact, these days it hardly needs any interest from the public in an event for the media to get itself stuck in a positive feedback loop. If it is a ‘quiet news week’ then any event that the media perceives as being important (to the media) can spiral into a continuous coverage frenzy, with the mere fact that lots of media people are covering it becomes a reason in itself for others to follow. An example of this in the UK was in December 2004, when the media spent most of its time and newsprint on two fairly trivial (and unrelated) events involving the Queen’s butler, and Cherie Blair. These have now been forgotten, but at the time they occupied the entire attention of the media, to an extent which puzzled most viewers and readers, as many people had little interest in them.

Which all goes to show how deceptively dangerous positive feedback can be