Burglars experts at navigating homes

They are also fast, focus only on high-value areas of a house, including bedrooms, studies and living rooms, are suspicious of unusual rooms, rarely enter bathrooms, and are more likely to take a few high value items than lots of lower value items.

Dr Claire Nee, of the University of Portsmouth, ran a study piloting two new methods in which burglars and non-burglars were asked to conduct a mock burglary. The experiments were designed to shed light on the cognitive processes of offenders, about which little is known. The results add to emerging research, pioneered by Dr Nee, that serial offenders demonstrate skills and strategies used by experts in any field.

Dr Nee said: "It sounds obvious that people who have been jailed for committing serial burglaries are experts at stealing, but we didn't have any understanding of what exactly they do or don't do which sets them apart from novices. We didn't know how they think or the way they approach the job of stealing. We have interviewed many offenders before but this time we were able to observe them for the first time.

"The findings have important lessons for crime prevention and suggest that if you've got something valuable you really want to protect, you might be better off hiding small things among the toothpaste tubes. Trying to get into the mind of the burglar would also help -- we leave opportunities for them everywhere."

Dr Nee and colleagues tested six serial offenders and six people with no criminal records in two separate tests. One test was to burgle a real house wearing a head-mounted camera and a motion capture suit, touching anything they would choose to steal. In the second test, they carried out the same crime in a virtual house on a computer designed at the University of Sussex, clicking with the mouse on any item they would steal.

All were then asked to talk through the footage taken on the head-mounted camera of them stealing, discussing their thinking and methods.

Dr Nee said: "When you're an expert it's hard to verbally articulate what you're going to do as it's automatic. It's much better to watch what people do, but this is difficult in crime science. The study highlighted that burglars approached the simulated house almost identically to the real house, which means we can develop simulations to safely observe offending behaviour and use them with large populations of convicted offenders. Using these simulations, we can also try out various crime prevention techniques which will stop the offender in his tracks and shock him out of his tried and tested habits. This will increase his anxiety and the likelihood of the crime being abandoned."

In both tests, all the experienced burglars entered the houses by the back door, while all the novices entered by the front door. All the burglars navigated the house in a systematic way, half heading straight for the upstairs bedrooms and avoiding bathrooms, before returning downstairs and checking the higher value rooms, and half doing the same in reverse. All but one of the burglars took identical routes upstairs, while the novices took haphazard routes around both houses.

Burglars spent more than twice the amount of time than novices in downstairs rooms, which are generally considered to contain more high-value items, while novices spent the same time in every room in both houses.

Burglars and novices took a similar number of items, but the burglars' hauls were worth about £1,000 more and included designer handbags, wallets, cash, phones and leather jackets, most of which had been ignored by novices.

Both the real and the virtual houses included an unusual room set up to look like a recording studio. The burglars were suspicious of this and spent much less time in the room, taking, on average five items, while novices had no qualms and stole, on average, 26 items from the room.

Dr Nee said: "As expected, the burglars were much more efficient, systematic and persistent than the novices. Through deliberate practice and repeated exposure to the layout of houses, burglars can automatically recognise which are the high-value areas of the house. Two key features of experts in any field are that they can instantly recognise features of the environment that signify a successful outcome and then behave more-or-less automatically to reap the rewards based on their finely honed skills. This makes their behaviour much more predictable than a novice, who will be haphazard.

"Outside the field of crime, scientists have seen that people behave in the same way in real and virtual environments. Simulated environments are widely used to train surgeons, pilots and soldiers, so the virtual house triggering almost identical behaviour in all those taking part is significant. It allows us to recreate many more and varied settings to run further tests."