Reposted from ScienceDaily:
http://www.sciencedaily.com/releases/2007/03/070307161756.htm

Every parent of a young child knows how emotionally attached children can become to a soft toy or blanket that they sleep with every night.

New research, published today in the international journal Cognition, suggests that this might be because children think the toy or blanket has a unique property or 'essence'.

To support this theory, Professor Bruce Hood from the University of Bristol and his colleague Dr Paul Bloom of Yale University, USA, showed that 3-6 year-old children have a preference for their cherished items over apparently identical duplicates.

Children were introduced to a scientific looking machine that could copy any object but was in fact a conjurer's cabinet where an accomplice inserted replica items from behind a screen.

Professor Hood said: "When offered the choice of originals and copies, children showed no preference for duplicates of their toys unless the object to be copied was the special one that they took to bed every night. A quarter of children refused to have their favourite object copied at all, and most of those who were persuaded to put their toy in the copying machine wanted the original back."

It used to be thought that these attachment toys or transitional objects were comfort items that provided a sense of security for infants raised in households where they slept separately from the mother.

However, the results with the copy box studies suggest that in addition to these physical properties of the toy, children believe that there is some other property of their objects that cannot be physically copied.

This unique property also applied to objects belonging to famous people. Hood and Bloom placed a metal goblet in the copying machine and told 6-year-olds that the object was special either because it was made of a precious metal or because it once belonged to the Queen.

When shown the original and a copy, children thought the duplicate silver goblet was worth the same as the original, but a goblet that once belonged to royalty was worth more than any copy.

Hood and Bloom liken this early reasoning to adult notions of 'essences' where we think invisible properties inhabit objects that make them unique as if these properties were physically real. This may explain why some adults think that authentic works of art and memorabilia contain some of the essence of the original creator or owner. Likewise, it also partly explains our reluctance to touch or wear items previously owned by murderers.

Case study:

The desperate plea for the return of Laurel's 'Mouse' shown in the poster stuck to the gates of a local park in Bristol, shows how distraught parents can get when these items go missing.

Sadly Mouse was never found but someone took a picture of Mouse to their mother who very kindly knitted a copy for Laurel. But Laurel spotted the difference and although delighted to have a replacement for Mouse, she didn't develop the same attachment to it that she had had for the original.

Note: This story has been adapted from a news release issued by University of Bristol.