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ABOUT 30 years ago, Ed Cornell, a psychologist at the University of Alberta in Edmonton, took a call from the police officer leading a search for a 9-year-old boy. The boy had gone missing from a campsite some days earlier, and his footprints suggested he had headed in the direction of a swamp a few kilometres away. The officer had one question: how far do lost 9-year-olds tend to travel?

Cornell and his colleague Donald Heth had been studying wayfinding behaviour for several years, so they were the obvious people to ask. But when they started pondering it, they realised how little they knew – how little anyone knew – about lost children: how they behaved, the routes they took, the landmarks they used, how far they went. Cornell and Heth quickly reviewed relevant studies and told the officer as much as they could. “His response shamed us,” they wrote afterwards. “‘Well, that’s not much. Don’t worry, doc, we may get a psychic out here today.'”

The way people behave when they are lost has always been a mystery, and searches were for a long time essentially random. But over the past decades, Cornell and other experts have dissected the available data in an attempt to understand how adults and children behave when they lose their way. Their aim has been to bring science to bear on searches, combining behavioural studies, statistics and probability theory to increase the chances of finding people before it is too late. Although they have discovered that lost people behave in extraordinary and irrational ways, they have also found that such individuals share certain habits that might help others to find them.

Search-and-rescue operations often involve scouring vast expanses of wilderness with limited resources, so anything that can help whittle down the area in which someone is most likely to be found is vital. That means knowing the landscape, of course, but also understanding how people behave when they are lost. The job of finding them is as much a psychological challenge as a geographical one. The trouble is that the behaviour of lost people is so confounding that predicting their movements is extremely hard.

What is clear is that lost people rarely do much to help themselves. In fact, they are likely to make things worse by continuing to move, which substantially reduces the chances of being found alive. Kenneth Hill, a psychologist at Saint Mary’s University in Canada, says most lost people are stationary when rescuers reach them, but only because they have run themselves into the ground and are too tired or ill to continue. In a review of more than 800 search-and-rescue cases from his home state of Nova Scotia, Hill found only two in which the person had stayed put: an 80-year-old woman out picking apples and an 11-year-old boy who had taken a survival course at school.

“The extreme stress of being lost makes it impossible to reason”

The urge to move is triggered by fear, which readies the body for flight from a threat by releasing hormones such as adrenaline into the bloodstream. Fear of being lost is as visceral as our response to snakes, and appears to be hardwired in brains the human brain: millions of years of evolution have taught us that the experience tends not to end well. People who are truly lost are often convinced they are going to die. Understandably, they are terrified.

This helps explain their erratic behaviour. The extreme stress of being lost makes it almost impossible to reason or figure out what to do. When fear kicks in, even experienced hikers fail to notice landmarks, or fail to remember them. They lose track of how far they have travelled. They feel claustrophobic, as if their surroundings are closing in on them. “It’s essentially a panic attack,” says Robert Koester, a search-and-rescue specialist based in Virginia with a background in neurobiology. “If you are lost out in the woods, there is a chance you will die. That’s pretty real. You feel like you’re separating from reality. You feel like you’re going crazy.”

It is pretty much impossible to run controlled experiments on people lost in the wilderness because of the genuine risk they could die. But there is plenty of evidence that high levels of stress affect the cognitive functions needed for wayfinding. Much of it comes from research on military recruits. In one study, Charles Morgan, a forensic psychiatrist at the University of New Haven in Connecticut, and his colleagues tested the mental performance of pilots and aircrew while confined in an oppressive mock prisoner-of-war camp. Their working memory and visuospatial processing – both of which are necessary for map-reading, spatial awareness and other navigation tasks – were so poor that they were performing at a level commonly seen in children under 10.

Little wonder that search-and-rescue veterans tell of lost people walking trance-like past search parties, or running off and having to be chased down and tackled. That is a problem not only for those doing the searching, but also for researchers attempting to understand what goes through people’s minds when they are lost. Cornell has found it is difficult to interview someone right after they have been found because “they are basically scrambled”, with little recollection of what happened. “You’ll never be able to figure out why lost people make their decisions,” says Richard Tomin, who worked for three decades as a search-and-rescue coordinator for the states of Vermont and Massachusetts.

Finding patterns

What science can do is identify predictable behaviours that could help rescuers narrow their search areas. You can usually take it for granted that your quarry has freaked out and ventured further into the unknown. What you really want to know is what they may have done next. To answer this, researchers have turned to the best data they can find: records from tens of thousands of searches in the US, Canada, Australia and the UK. They have focused on aspects of behaviour that are easy to measure, such as how far and for how long someone travels before being rescued, the degree to which they stray from their intended course, the type of place they end up and, crucially, whether or not they survive.

, intuitive to all humans in unfamiliar landscapes. We are all drawn to boundaries, such as the edge of a field, a forest margin, a drainage ditch, a line of pylons or the shore of a lake. Overall, most lost people who are found alive end up in a building or on what rescuers call a travel aid: a road, track or path, say, or an animal trail. Rescuers now know to always scout out such features first. It is a strategy of probabilities: once you have ruled out the most likely places, the chances increase of finding someone elsewhere.

But real cases also reveal that many predictable tendencies vary according to a person’s age and gender, their mental state and what they were doing when they got lost. Children are less likely than adults to keep moving, for instance, which explains why 96 per cent of them are found alive compared with 73 per cent of adults. Children with autism, meanwhile, usually take refuge in some kind of structure, whether it is an outbuilding, a shed or even a thick bush. People with dementia tend to head in a straight line through whatever lies in their way. And solo male hikers, once lost, travel much further than any other category of missing person. They just keep on walking until someone finds them.

“When people with dementia get lost, they tend to head in a straight line”

In other words, different types of people get lost in different ways. This insight can make a big difference to a search coordinator, provided they have enough information about the person they are looking for. Taking into consideration the specifics of the person and the terrain, it is possible to estimate the area in which they are likely to be found or the route they may have taken, and then adjust that estimate as a search progresses. “The idea is to get inside their head and predict how they will behave in the situation they find themselves in,” says Dave Perkins at the Centre for Search Research in Northumberland, which collates missing person data in the UK.

Although it is difficult to quantify success rates, most search-and-rescue coordinators are convinced that the use of statistics and probability a more scientific understanding of behaviour have improved the chances of finding lost people. But they are also quick to point out that locating a missing person alive often depends to a great extent on having even a few scraps of real-time information and a bit of luck.

One case that illustrates this is that of Geraldine Largay, a 66-year-old who, in July 2013, went missing in dense woodland near Redington in Maine while walking the Appalachian Trail. Despite the deployment of a highly experienced search team and plentiful resources, including spotter planes and helicopters, she wasn’t found. The investigation didn’t turn up a single clue about what had happened to her until her remains were discovered two years later, still in her sleeping bag. The problem was that her rescuers had nothing tangible to go on, and no amount of science can make up for a lack of information.

Largay had done everything right. When she realised she was lost and had no phone signal, she headed for high ground, where she was more likely to be spotted, pitched her tent and waited for help (see “Get found!”). She didn’t know that a dog team passed within roughly 100 metres of her, that her campsite was less than a kilometre from the trail as the crow flies or that if she had walked downhill she would have soon reached an old railroad track that would have taken her, in either direction, out of the woods.

Researchers striving to make such a tragic outcome less likely are handicapped by the fact that they can never be there when the action unfolds. They can learn something about the way lost children move, however, by observing them when they aren’t actually lost. Children tend to get lost while wandering aimlessly rather than heading for a destination, and watching them in action can be instructive.

After Cornell’s deflating call from the police officer searching for the 9-year-old boy, he and Heth ran an experiment. They contacted the parents of 100 children aged between 3 and 13 who lived on the edge of the prairies and, with the full permission of everyone involved, asked each child to lead them to the furthest place from home they had visited on their own. Cornell and Heth followed behind, watching what they did, recording their route and measuring distances. The children made all the decisions and could rest, walk home or call their parents whenever they wanted.

The study was the first time anyone had cast a scientific eye over how children navigate. It turned up some surprising results. Their major finding was that children, when left to roam by themselves, travel much further than anyone, especially their parents, think they do – 22 per cent further, on average, than expected, and in some cases three or four times as far. But what really interested Cornell and Heth was how they travelled. None went to the target location directly. They wandered, dawdled, got distracted and took long, circuitous diversions.

“They would climb a fire hydrant to get a better view, kick a pile of leaves, throw rocks or stop to watch a barbecue,” says Cornell. “They seemed to follow their natural inclinations. Many of them freely admitted they were off the path they thought they knew.” The researchers published their findings in the journal of the US National Association for Search and Rescue. As well as maximum distances, they included data on walking speed, likely direction of travel and other variables they felt might help rescuers estimate the path of a lost child.

Some time later, Cornell again received a call from a police officer leading a search for a lost child. He prepared himself for the worst. While the chances of finding lost children were considerably better than when he and Heth had begun their research, the 9-year-old who had inspired their work had never been found and the loss still felt raw.

But the officer had good news. He was calling to let Cornell know that his team had just found a missing 3-year-old boy, using the data he and Heth had published on likely distance travelled and favoured destinations – and when they found him, he was minutes away from dying of hypothermia.

• Michael Bond is the author of Wayfinding: The art and science of how we find and lose our way (Picador)