Have you ever skidded in the ice or snow? If so you'll know it is a deeply disturbing feeling. This is partly because it is dangerous, but that's not all. Normally when you turn the wheel the car goes in the right direction, but suddenly this no longer happens, the car seems to have a life of its own. But it's not even the out-of-control feeling that is disturbing. You have come to intimately associate your physical actions with movement on the road, the car has become an extension of your body. When turning the wheel ceases to turn the car, it is like a limb that has ''gone-to-sleep at night, a part of your body that has become separated.

There is an extent to which the car has become an extension of ourselves ­ the driver and the car together are a cyborg.

If you give instructions to a driver, you may say "turn right at the next junction". However, 'turn' could be used in the intransitive sense "turn the car" or transitive "turn yourself". If I asked you what you were doing as you drove the car, you would almost certainly use words such as "I'm turning at the next junction". You are unlikely to say "I'll turn the car at the next junction". The exceptions to this are activities such as 3-point turns or reverse parking when references to the car and wheels become more common. [[is this also true in other languages with different ways of expressing transitive and intransitive verbs?]]

Think also of the sense of space on the road. You may have a region of, perhaps a metre or so each side and perhaps 20-50 metres in front which is 'personal space'. Other cars that intrude into this may be perceived as 'crowding you'. A car close behind may be described as 'tailboarding' (third party language) but may also be described 'up my bum', a very personal association with the car!

the boundaries of self

The idea of personal space is very important in social situations, and we resent or feel disturbed when people enter into our personal space. In normal corporeal life, we are faced with situations where we modify our personal space, such as in a crowded bus. In a traffic jam drivers may turn up the radio and assiduously avoid catching the eye of drivers beside them, or the rear-view mirror of the car in front. Exactly the same reactions as we have within crowd situations.

This blurring of the boundaries of self to include artefacts and tools is not uncommon. We are often not explicitly conscious of clothes, wristwatches, jewellery, spectacles. To some extent the classic 'going out undressed' dream is a recognition of this, we are so unaware or our clothing that it is conceivable that we could not notice that we don't have any! Strangely enough, few of us, if asked to 'picture ourselves' in our heads would do so naked without prompting.

Medical procedures can often shock this sense of self, a joint replacement, pace maker or transplant, each push our acceptance of the other as part of our self. There are even psychological conditions where patients reject some part of themselves, regarding a leg or arm as somehow 'not theirs' and may seek to mutilate or remove the offending limb. Our sense of self is clearly fluid, and necessarily so, else how would we be able to continue to accept 'ourselves' as we grow and mature, but can misbehave.

ready to hand

Quite influential in the study of user interfaces as 'tools' has been ideas of 'breakdown' - points at which we become conscious that we are using a tool, rather than simply using it. When things are going well, we do not think about wielding the hammer, but hitting the nail. It is not just 'ready to hand', but has become and extension of our arm. The cyborg experience is perhaps an extension of tool use. But if the hammer head becomes loose, or our hand slips on the grip, suddenly the illusion is broken and the hammer becomes a 'thing'. As well as often reducing the efficiency of the interaction, breakdown reduces the sense of fluidity and engagement and, if the sense of one-ness with the tool was great, a feeling of disjunction.

There are also clear links to the sense of engagement and presence in virtual reality. Certainly the intimate and immediate connection of control, interaction and feedback are central to feelings of immersion. However, it is not that the user is entering some sort of cyborg identification with the virtual environment, anymore than we do with the physical world. Instead, engagement represents an identification of self with the virtual agent which moves and acts within the virtual environment. The avatar as virtual cyborg.

Engagement itself is not sufficient to engender a feeling of presence. The ability to perceive one's own embodiment in the environment is central. At first this seams strange, the naturalness of our body means that we are not explicitly aware of it, and indeed to become aware of it is almost always a sign of breakdown (either medical problems, or some form of social self-consciousness). However, this lack of explicit awareness belies the constant sub-conscious awareness of ourselves, through peripheral vision, kinaesthetic senses etc.

In particular, our ability to move parts of our bodies to absolute spatial locations is good, but requires constant recalibration with the environment ­ try writing with the light out! Fitts' law is a good example of this, the logarithmic time to hit a distant target can be modelled as a control phenomenon with visual feedback required to re-establish the relationship between our finger (or indirect computer pointer) and the target.

It is easy to forget this importance of peripheral self awareness. In a recent television programme a researcher at MIT was attempting to train a humanoid robot mimicking a child's mental growth. At one point the researcher had finished the 'mimicking' procedures. As the researcher moved his right hand in the view of the robot's camera eye, the robot moved its right hand in mimicry. But note, the right hand. Try this with a real baby! The robot could 'see' the researcher's hand move, but through the narrow field of view of a television camera, it could not 'see' its own hand. Central to a sighted baby's development is the association of 'this feeling' with 'that thing' out there, which happens to be the baby's own hand, followed by the realisation that it is possible to make 'that thing' do stuff and so gradually become 'my hand'. Note that control and awareness lead to identification with self.

the naked tool-user

So where do we get this ability to assimilate other objects into our sense of personal being that makes the cyborg experience possible?

One answer has already become apparent. For normal development we need to learn what is and is not self. This cannot be built into our genetic code. Even to recognise that something is a hand is almost certainly too complex, but, to know which of the hands that are close to me is mine and which is that of my colleague? This surely cannot be pre-programmed and instead we have the ability to learn the associations. Furthermore, as we saw, this must be a fluid association to allow us to grow, age, and possibly suffer disfigurement or injury without rejecting our self.

These associations however are learnt slowly over months and years. What of the ability to get into a car and drive, rather than be in it, or to take up a hammer and make something, rather than wield it? Tool use is itself very old and certainly not confined to humans. I always assume that our ability to move a cursor on screen by moving a mouse on a mat must be related to a chimpanzee's ability to manoeuvre a stick and pick grubs out of a hole. This is a truly amazing ability, the understanding that a physical movement of this end of the stick has an effect at the other end! Does a chimpanzee feel the same feeling if dislocation if the stick bends that I feel in a skidding car?

These feelings of social oneness and corporeal extension perhaps come together in the potentate, absolute monarch, dictator or even constitutional leader. Notice that the Queen says 'we' never 'I'. Group leadership can engender a loss of separation between self and group: one's 'fiat' becomes action and hurt in the group is felt personally. Have there been and psychological studies of dictators during a fall from power, a president facing impeachment, or even elected leaders as they approach the end of office? Is the loss of control also felt as a breakdown in self?

the social I

Even ordinary members of the group although experiencing that sense of personal control over the group's behaviour are perhaps aware of the group's own intent, actions and effects on the world. On September 11th, the people of the United States lost many loved ones, felt themselves in danger and experienced with most of the western world, a sense of uncertainty and breakdown in the world order. However, again and again one heard words suggesting a sense of violation - personal, intimate, violation. In all countries the sense of occupation or attack 'on our own soil' is deeply disturbing as we experience an infringement of our super-corporeal self. This is equally true in Afghanistan or Israel. The US experienced a double sense of dislocation because it had learnt to see 'its self' as having control and influence beyond its own borders, especially since the collapse of the eastern block, and so a challenge to this is perhaps not unlike the feelings of a runner with a broken tendon or wheelchair-bound dancer.

It is perhaps salutary to note that the US and western allies have tried to manipulate these ideas of selfhood in other nations. In Afghanistan, Iraq and, during the Kosovo campaign, Serbia there has been a strong emphasis that the fight is with the leadership not the nation. This has had some practical political advantages, not least legitimising military action without declaration of war and the associated inconvenience of the Geneva Convention! However, this propaganda has, in some case, also been crucial in allowing a population, facing enormous superior forces, to accept attack and defeat without the associated sense of violation of self and personal shame. Whether this is possible without some level of personal denial or national schizophrenia will remain to be seen. Certainly several nations went through a similar process after the Second World War.