This cartoon caused me both to chuckle and to think about the nature of the medium, and the dogs as a metaphor for subtle change. When we meet people in the flesh we immediately start to gauge their qualities. Clothing, mannerisms, choice of words and body language give us initial impressions of sincerity and trustworthiness. We also assess the possibilities for co-operation, working relationships and friendship, continually refining our perceptions. Interestingly, it is becoming important to do this faster and more accurately as computers and travel speed up human interaction.

We can now find ourselves meeting people a few times for short periods, but still having to make commitments and important decisions. When we use the telephone a similar process of assessment occurs based solely on conversation, tone and responses to questions, propositions and answers.

Even in a written letter there are subtle clues that allow us to build a mental model of the correspondent. Letter headings, physical address, font, handwriting, signature, content and style all help us to relax and become friendly, or stiff, cautious and defensive.

How different the world of email: communication is rapid, brusque and efficient, but where are the clues - is it a dog or a friend? Often we cannot tell until after the event. Friends will be open and honest, will protect messages and treat them as private conversations, and will broadly observe the normal protocols and behaviour we see in much of society. The rest can be graded from the naive and careless to the pernicious and mischievous. They copy messages to individuals who should never have seen them, or broadcast the contents to a public audience. The most difficult to deal with are those who quote out of context, or cut and paste modified text under your name and header. Presumably they derive some perverse pleasure from this process, but they are the dogs, and dangerous.

A friend once observed that I write as I speak. For me the pursuit of good communication pervades all my activities. As far as I can tell, my persona in the flesh is the same on the telephone, video-conferencing, radio and TV, letters and email. Curiously, I find this not to be the case for a good deal of the human race. I observe people saying, writing and mailing things they would never say face to face.

It is as if technology affords them some cloaking device, releasing parts of their personality not normally visible. And I do not decry this when used positively - I see some brilliant communicators who use this to great advantage. It can be a terrific skill. For many of us, however, I suspect we need a new notice on the road to the superhighway - "Beware of the dogs".

Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is:
http://cochrane.org.uk