Any rational person in the UK who doesn't want to be left without petrol has probably topped their vehicle up recently or at least thought about doing so. After all, the people running the country, before changing their advice today, had advised drivers to do this, amid fears of a country-wide strike by tanker drivers.

When consumer behaviour changes on a mass scale in this way, the media usually work up a lather, pronouncing that the country is in the grip of "panic buying" or "mass hysteria". In fact, most drivers are behaving calmly, doing the sensible thing based on the information they've received.

The situation began a few days ago when, for political and practical purposes, the coalition government started to publicise the strike threat and talk about the contingency plans they were putting in place. The last thing any government wants is to be blamed for not planning ahead or to be accused of not giving people due warning. By putting contingencies in place and encouraging stockpiling, the coalition also presumably hoped to undermine the potential impact of a strike, thereby dissuading the tanker drivers from fulfilling their threats in the first place.

Unfortunately, the government's early announcements and warnings invoked three of the most powerful principles in the social psychology of persuasion, as outlined by the doyen of the field, Robert Cialdini, Regents' Professor Emeritus of Psychology and Marketing at Arizona State University, in his book Influence: Science and Practice.

The first of these is "authority" - we tend to listen to people we perceive as knowledgeable or having privileged information. Despite the lousy reputation of politicians, when several members of the coalition said repeatedly that fuel could run low, many people believed them and started changing their buying habits.

Second is the "scarcity principle" - we instinctively want what we can't have and value highly that which is rare. Once people started to believe that fuel is in short supply and that it could run out, they immediately wanted it more and were willing to work harder to get it, for example by queuing or taking unplanned detours to forecourts. For other examples of this effect in action, just look at the way parents behave around Christmas time when rumours emerge that a trendy toy is due to sell out; or consider the way Concorde tickets became hot property the moment it was announced the jet would soon fly no more.

The last relevant factor is known as "social proof" or "social norms" and is perhaps the most powerful of all. Time and again research has shown that we tend to look at how other people are behaving (or how we think they're behaving) to help choose how we should behave ourselves. Take the context of binge drinking by university students, where it's been found that most undergrads massively overestimate how much their peers drink and then use this mistaken yardstick to guide their own drinking patterns.

With regard to the fuel situation, many people probably decided that they weren't too concerned and some may still feel that way. But the sight on the news of people queuing for fuel is incredibly compelling. Because it's human nature to copy each other, if we see that everyone else is filling up, we're likely to do the same. Twenty-four hour rolling news online and TV makes this factor more powerful today than ever before.

The net result of all this is that some fuel pumps around the country are running dry even though the strike may not even happen. Of course, lack of fuel in the pumps serves to fuel the news story, creating a self-perpetuating situation - though to call it hysteria or panic is hyperbole. Only now the message has been communicated from trusted sources that there's plenty of fuel, and that most people aren't stockpiling, will normal service likely be resumed.

Dr Christian Jarrett is a psychologist and author of The Rough Guide To Psychology