According to psychologists, children develop sentimental attachments to cuddly toys, blankets, and even smelly old bits of material because they intuitively feel they possess a special meaning or life force. Children chose their cherished comfort blankets or favourite raggedy bear over duplicates that seemed to be identical, according to a survey that would surprise many parents.The findings indicated that even very young children believe in intrinsic values that cannot be duplicated in such items.

The study found children's reaction was similar to that of art collectors who favour an original to a replica that is comparable in any way. According to previous research, up to 70% of small children form deep bonds to items such as toys or blankets. The syndrome is often limited to the Western world, where children begin sleeping away from their parents at a young age.

Bruce Hood of the University of Bristol and Paul Bloom of Yale University in the United States agreed to investigate whether this was the case. Parents were asked to carry their three to six-year-old children into a laboratory with their "attachment piece" or, if they did not have one, a favourite toy or doll. The infant had to sleep with it on a daily basis and have had it for at least a third of his or her life to qualify as an attachment item.

The children were shown a "copying machine," which was really a conjuror's cabinet made up of two boxes. The two boxes' doors were opened, and a green block was placed within one of them. The doors then closed, an experimenter twiddled a few knobs, and the first box buzzed. A buzz emerged from the second box a few minutes later. The experimenter had slipped a similar block into the second box, so the doors of both boxes opened to reveal a green block in each.

The experimenter then asked the kids if they agreed to have the items they carried in copied. They had the option of taking the new one or returning the old one. Those that had "non-attachment" objects enabled them to be copied, and almost two-thirds chose to retain the "new" one, which was still their own. Four of the 22 children who had attachment items were adamant on not allowing them to be replicated at all. Just five of the 18 people who agreed to have their valuables copied chose the "duplicate."

Finally, both of the children were told how the illusion performed, ensuring that they had their original object back. Prof Hood explained that the experiment revealed that children assume that their items have a consistency that cannot be duplicated in addition to their physical properties.

He said: "If there was a machine which copied a favourite object in every way down to atomic level, we would still prefer the original. It has an essence to it. This experiment suggests this is an intuitive process. "We anthropomorphise objects, look at them almost as if they have feelings. The children know these objects are not alive but they believe in them as if they are."

Although it is widely assumed that sleeping with a comfort blanket is mostly a western characteristic, Prof Hood claims that object have an essence is not. Some eastern traditions hold that something has a life force, and some societies find it impossible to reside in other people's homes since they believe there is an invisible remnant of the former inhabitants.